(Lotus 1-2-3). The standard extension for Lotus 1-2-3 spreadsheets. Popular in the 1980s and 1990s, discontinued in 2013. Still supported by converters.

(T602 Document). A text processor format developed in Czechoslovakia in the late 1980s for DOS. T602 was widely used in Eastern Europe, offering word processing with Central European character support. Files contain formatted text and basic layout. Obsolete today, but historically important in local computing history.

(Portable Network Graphics). PNG was created in 1995–1996 by the PNG Development Group, coordinated by Thomas Boutell, as a patent‑free replacement for GIF after the Unisys LZW licensing dispute. It uses lossless DEFLATE compression in a chunk‑based structure and supports indexed color, 24‑bit truecolor, and up to 16‑bit per channel images, plus full alpha transparency. Unlike GIF, core PNG deliberately omitted animation; APNG arrived later as a separate extension. PNG’s sweet spot is crisp web graphics—UI icons, logos, screenshots, and line art—where sharp edges and transparent backgrounds matter more than tiny files. It is less efficient than lossy formats for photographs, since preserving every pixel typically yields larger files than JPEG at equivalent visual quality. Designers still lean on PNG because it is universally supported by browsers and operating systems, decodes predictably, and preserves pixel‑perfect detail without generation loss. In print or archival tasks it appears when exact pixels are required and TIFF would be excessive. Newer formats like WebP and AVIF can beat PNG on byte size, but when simplicity, compatibility, and honest transparency are priorities, PNG remains a dependable default.

(Joint Photographic Experts Group). JPG is the three‑letter filename extension for images encoded with the JPEG standard (ISO/IEC 10918‑1; ITU‑T T.81). The shorter “.jpg” spelling became common on DOS/Windows systems that limited extensions to three characters; functionally it is identical to “.jpeg.” JPEG’s joint ISO/IEC and ITU committee specified a DCT‑based, lossy codec optimized for natural photography: it discards imperceptible detail, works on 8×8 blocks, and often uses 4:2:0 chroma subsampling to reduce color data safely. By the mid‑1990s every digital camera, editor, and browser supported it. Today .jpg files dominate photo workflows on phones, CMSs, and social platforms. They excel on complex, continuous‑tone imagery where transparency is not needed. The trade‑offs are familiar: blockiness at low bitrates, halos on sharp edges or text, and no alpha channel or high bit depth. Progressive JPEG and careful quality settings help, but for logos or UI art you’re better off with PNG or SVG. For everyday photos, .jpg remains the default because it is small, fast, and universally compatible.

(Joint Photographic Experts Group). JPEG is the image compression standard created by a joint ISO/IEC and ITU‑T committee and first published in 1992. It defines the core coding pipeline—color transforms, 8×8 discrete cosine transform, quantization, and entropy coding—while practical interchange commonly uses JFIF or Exif wrappers. The original motivation was a royalty‑free, hardware‑friendly way to store and transmit photographs over slow networks and limited storage. It delivered: JPEG enabled early digital cameras, consumer photo printing, and the first web galleries. Modern use still favors JPEG for broad compatibility and mature tooling; virtually every device can decode it efficiently, often in hardware. Enhancements like progressive mode and optimized Huffman tables can yield excellent quality at moderate sizes, yet JPEG lacks some modern features: no alpha transparency, limited bit depth, and visible artifacts at aggressive compression. Newer contenders (JPEG XL, HEIC/HEIF, WebP, AVIF) surpass it in compression efficiency and features, but JPEG endures as the universal common denominator for photographic images across software, browsers, and archives.

(Graphics Interchange Format). Introduced by CompuServe in 1987, GIF is a bitmap format with support for simple animations via frame sequencing. While inefficient compared to video codecs, GIFs became a cultural staple for memes and loops because they work everywhere.

(Bitmap). BMP—formally the Device‑Independent Bitmap or DIB—is Microsoft’s native raster format dating to Windows 3.0 (1990). It was built for straightforward, byte‑addressable pixel storage with optional color tables and minimal or no compression, tailored to Windows GDI. BMP supports a spread of bit depths (1, 4, 8, 16, 24, 32 bits), row paddings, and, in later revisions, simple RLE compression. The goal wasn’t efficient web delivery; it was predictable rendering and easy interchange among Windows applications, drivers, and toolchains. Because BMP stores pixels almost verbatim, files are large but decode instantly and without quality loss, which suited early screen capture, testing, and embedding resources. Modern workflows rarely ship BMP over networks, but it persists in legacy systems, firmware graphics, and low‑level tooling where simplicity beats efficiency. For distribution or archiving, better choices abound: PNG for lossless web graphics, TIFF for high‑fidelity pipelines, and JPEG/WebP/AVIF for compact photos. BMP’s value today is its radical simplicity—it is so basic that it almost never surprises you.

(Tagged Image File Format). TIFF was created by Aldus Corporation in 1986 to standardize the exchange of scanned images for desktop publishing; Microsoft partnered on early versions, and Adobe assumed stewardship after acquiring Aldus in 1994. TIFF is not a single codec but a flexible, tag‑based container capable of bilevel, grayscale, palette, and full‑color images at high bit depths. It supports multiple pages, tiled storage, extensive metadata (including EXIF and XMP), and a menu of compressions: PackBits, LZW, Deflate/ZIP, CCITT Group 3/4 for fax, and even JPEG inside TIFF. That adaptability explains its longevity in prepress, cultural‑heritage scanning, scientific microscopy, and geospatial work (GeoTIFF). TIFF files can be large, and interoperability sometimes suffers when vendors rely on private tags, but when a shop requests master assets, TIFF is usually implied. It’s heavy for the open web yet ideal for archival and production pipelines that need exact pixels, color profiles, and metadata to survive round‑trips without surprises.

(Tagged Image File Format). TIF is the three‑letter extension variant of TIFF, a holdover from DOS/Windows limits on filename extensions. The underlying format is identical: a tag‑based container born at Aldus (1986) and maintained by Adobe, able to store high‑bit‑depth imagery, multipage documents, tiled pyramids, and a range of compression schemes including LZW, Deflate/ZIP, PackBits, CCITT Group 4, and embedded JPEG. Some organizations standardize on .tif for production masters and .tiff for working files, but this is convention, not a technical difference. Modern uses mirror TIFF’s strengths: scanning masters from flatbeds and film, prepress hand‑offs with embedded ICC profiles, scientific imagery with rich metadata, and geospatial layers via GeoTIFF. For lightweight sharing or the web, convert to PNG/JPEG/WebP; keep .tif for source‑of‑truth files that must preserve pixels and metadata across decades.

(Web Picture). Google’s modern image format introduced in 2010. In addition to still images, WebP supports animation using VP8 frames. It offers much smaller file sizes than GIF while retaining better color and transparency. Supported across modern browsers and apps.

SVG, or Scalable Vector Graphics, is an XML-based image format introduced by the W3C in 1999 to provide a standard for displaying vector graphics on the web. Unlike raster formats such as JPEG or PNG that rely on pixels, SVG uses mathematical equations to define shapes, lines, and text, which means graphics can scale infinitely without losing clarity. Its history is rooted in the need for a universal, lightweight, and resolution-independent format at a time when the web was rapidly expanding, and it has since become widely adopted for icons, illustrations, and logos. SVG is preferred because it keeps file sizes small, supports interactivity and animation through CSS and JavaScript, and ensures sharp rendering across devices and screen resolutions.

(AV1 Image File Format). AVIF is an image format based on the AV1 video codec and wrapped in the HEIF container. It was standardized by the Alliance for Open Media (AOMedia) in 2019, a consortium including Google, Mozilla, Cisco, Amazon, and Netflix. The aim was to push compression efficiency beyond JPEG and even WebP, while offering advanced features like HDR, 10/12‑bit depth, wide color gamut, and alpha transparency. AVIF’s lossy mode dramatically outperforms JPEG in size/quality trade‑offs, and its lossless mode competes with or exceeds PNG. AVIF supports animation as well, making it a candidate for GIF/WebP replacements. Adoption started slowly due to encoding/decoding complexity, but browsers like Chrome, Firefox, and Safari now support it. Tooling across CDNs, image libraries, and OSes is catching up. Today, AVIF is considered one of the most efficient all‑purpose web image formats, though it still requires more CPU to encode and decode compared to older formats.

(OpenEXR). EXR is a high‑dynamic‑range image format developed by Industrial Light & Magic (ILM) in 1999 and open‑sourced in 2003. It was built for visual effects pipelines where film and CG compositing require extremely wide dynamic range and high bit depth. EXR supports floating‑point pixels (16‑bit half and 32‑bit full), multiple image channels, deep image data, and lossless or lossy compression tuned for production workflows. Unlike consumer formats, EXR is engineered for accuracy, flexibility, and scalability, not compact file size. It’s common in VFX, animation, and CGI rendering, used by tools like Nuke, Houdini, and Blender. While unsuitable for web or casual use due to heavy file sizes and software requirements, EXR is essential in industries where retaining exposure latitude and visual fidelity is critical. It remains the standard in Hollywood VFX pipelines, scientific visualization, and high‑end photography experiments.

(High Dynamic Range Image). The HDR file format, often seen with .hdr or Radiance RGBE files, originated from the Radiance lighting simulation software developed by Greg Ward at Lawrence Berkeley National Laboratory in the late 1980s. It stores pixel values as RGB plus a shared exponent (RGBE), allowing representation of luminance beyond the 0–255 range of standard 8‑bit images. HDR was created to enable physically based lighting calculations and accurate rendering of real‑world brightness. Modern HDR workflows often use EXR for production, but the Radiance .hdr format still appears in 3D rendering, environment maps, and lighting research. It’s valued for simplicity and compactness while retaining a wide dynamic range. Though not common for end‑user photography, HDR images underpin HDRI lighting in computer graphics and serve as input to tone‑mapping operators in game engines and simulations.

(High Efficiency Image Container). HEIC is an implementation of the HEIF standard (High Efficiency Image Format) that specifically uses the HEVC (H.265) codec for compression. It was introduced by the MPEG group in 2015 and adopted widely by Apple starting with iOS 11 in 2017. HEIC stores single images or sequences, supports transparency, high bit depth, and advanced metadata. Its main draw is superior compression compared to JPEG: files are about half the size for similar quality. Apple’s adoption made it the default for iPhone photos, which forced industry support across macOS, Windows, and Linux tools. While technically more advanced, HEIC is criticized for licensing restrictions tied to HEVC patents, complicating universal support. Today it dominates on iOS and remains in use where Apple’s ecosystem leads, but web and cross‑platform scenarios often favor AVIF due to open licensing and broader industry push.

(High Efficiency Image Format). HEIF is a container format standardized by MPEG in 2015 as part of ISO/IEC 23008‑12. It is based on the ISO Base Media File Format (same family as MP4) and can hold images, sequences, auxiliary data, depth maps, and more. HEIF itself is codec‑agnostic; HEIC is the most common flavor that uses HEVC/H.265 compression, but HEIF can theoretically work with other codecs. HEIF was designed to succeed JPEG with smaller file sizes, support for 16‑bit color, alpha channels, burst photo sequences, and even animations. Its adoption surged via Apple’s ecosystem under the HEIC label, but patent encumbrances slowed broader embrace. HEIF’s role today is transitional: it underpins modern camera systems, especially mobile, and sets the stage for newer codec pairings (like AVIF with AV1) that address licensing headaches. It is a bridge format, powerful but politicized.

(Sony Alpha Raw). ARW is Sony's proprietary RAW image format used by its Alpha line of digital cameras. It is based on the TIFF/EP standard but contains Sony-specific tags and encoding of sensor data. The goal of ARW, like other RAW formats, is to preserve unprocessed sensor output before demosaicing or in-camera adjustments. This allows photographers to extract maximum dynamic range, adjust white balance, and apply custom processing later in software like Adobe Lightroom or Sony's Imaging Edge. ARW remains actively used across Sony's mirrorless and DSLR range, making it central to professional and enthusiast workflows.

(Canon Raw version 2). CR2 is Canon's second-generation RAW file format, introduced around 2004 with the Canon EOS 20D. It is based on TIFF/EP and stores minimally processed sensor data along with metadata such as camera settings, lens information, and embedded previews. CR2 files allow photographers to re-interpret exposure and color balance after capture, unlike JPEGs which bake in processing. Canon's Digital Photo Professional (DPP) and third-party editors support CR2 widely. Its main limitation today is that Canon has moved to CR3 for newer cameras, though CR2 files remain common in archives and legacy workflows.

(Canon Raw version 3). CR3 replaced CR2 starting with Canon's EOS M50 in 2018. It uses the ISO Base Media File Format container (the same family as MP4) instead of TIFF, enabling more flexibility. CR3 supports both Canon's traditional RAW and a compressed variant called C-RAW, which saves space with little visible loss. The shift also streamlined metadata handling and modernized the format for video-centric cameras. Today CR3 is Canon's active RAW standard across DSLRs and mirrorless bodies, though some compatibility gaps still exist in older software.

(Digital Negative). DNG was introduced by Adobe in 2004 as an open RAW format intended to unify the fragmented proprietary RAW landscape. Built on TIFF/EP, DNG includes flexible metadata, embedded previews, and profiles. Adobe's motivation was to future-proof archives by offering a published, royalty-free specification instead of relying on reverse-engineered proprietary formats. While adoption by camera makers has been limited (Pentax, Leica, and some niche vendors use it natively), DNG is widely used in mobile devices, drones, and as an archival format. It remains important in workflows where long-term accessibility is critical.

(Epson Raw Format). ERF is the RAW file format used by Epson's short-lived range of digital cameras in the early 2000s, such as the Epson R-D1. Structurally it is TIFF/EP-based and stores sensor output plus camera metadata. Its niche use and Epson's exit from the camera market mean ERF is largely legacy, but it can still be opened by RAW converters like Adobe Camera Raw or dcraw. Historically, it marked Epson's attempt to compete in serious digital photography; today, ERF mainly survives in archival contexts.

(Kodak Digital Camera RAW). KDC files were used by Kodak's consumer and professional digital cameras in the 1990s and 2000s. Like other RAWs, they are TIFF/EP derivatives holding minimally processed CCD sensor data. Kodak was an early digital pioneer, and KDC served as its native RAW format before the company's retreat from digital cameras. Today KDC is mostly of archival interest, supported by tools like dcraw and ImageMagick, but rarely encountered in active workflows. It represents an important part of digital imaging history.

(Mamiya RAW Electronic Format). MEF is the RAW image format used by Mamiya's medium-format digital backs, which catered to high-end studio and fashion photography. MEF files store the raw sensor data with metadata about capture conditions. While not widespread compared to Canon or Nikon formats, MEF remains important in archival workflows where Mamiya backs were used. Software support includes Adobe Lightroom, Capture One, and open-source libraries. Mamiya's role in medium format means MEF files often appear in high-resolution studio archives.

(Minolta Raw). MRW is the RAW format developed by Minolta for its digital cameras in the late 1990s and early 2000s. Like others, it is TIFF/EP-based and contains minimally processed sensor data. After Konica Minolta merged and later transferred its camera operations to Sony in 2006, MRW was discontinued. Legacy files are still supported by many RAW converters, but no new cameras produce MRWs. They mark an important chapter in digital photography's evolution, bridging early consumer digital cameras and the Sony Alpha era.

(Olympus Raw Format). ORF is the RAW file format used by Olympus digital cameras. It captures minimally processed sensor output, providing maximum latitude for post-processing. ORF includes camera-specific metadata, including Art Filters and picture settings. While not as widely known as CR2 or NEF, ORF files are fully supported in major editing suites. Today, ORF remains the default for Olympus/OM System cameras, particularly in Micro Four Thirds. It is favored by enthusiasts who want maximum control over image development.

(Pentax Electronic File). PEF is Pentax's proprietary RAW format, based on TIFF/EP. It stores sensor data plus metadata specific to Pentax cameras. Introduced in the early 2000s, PEF remains supported in Pentax's DSLR line, though many models also allow DNG capture, aligning with Adobe's open standard. PEF is widely supported by editing tools and ensures Pentax shooters retain full control over image processing. Its continued use reflects Pentax's niche but loyal user base.

NEF (Nikon Electronic Format). NEF is Nikon’s proprietary RAW image format, first introduced in the late 1990s with its digital SLRs. Built on the TIFF/EP standard, NEF files store unprocessed sensor data along with extensive metadata such as camera model, lens info, white balance, sharpening, and picture control settings. This gives photographers full latitude to reinterpret exposure and color in post-production. Nikon’s Capture NX and ViewNX software handle NEF natively, while third-party editors like Adobe Lightroom and Capture One provide broad support. Unlike JPEG, which bakes in processing, NEF preserves maximum dynamic range and detail. The trade-off is large file sizes and the need for compatible software, but NEF remains central to Nikon shooters because it enables precise adjustments without degrading quality. For archival, editing, and professional workflows, NEF is considered the ‘digital negative’ of Nikon photography.

(Raw Fujifilm). RAF is Fujifilm's proprietary RAW format for its digital cameras. It contains unprocessed sensor data and metadata about capture. Fujifilm is notable for using unique sensor designs, such as X-Trans, which differ from Bayer layouts. As a result, RAF files often need specialized demosaicing for optimal results. Fujifilm's software and third-party tools like Capture One provide tailored support. RAF remains central to Fujifilm workflows, ensuring maximum image quality and creative flexibility.

(Panasonic Raw). RW2 is Panasonic's RAW file format used in its digital cameras, especially the Lumix line. Like other RAWs, it is TIFF/EP-based but contains Panasonic-specific metadata and compression schemes. RW2 files offer photographers the flexibility to reprocess images without quality loss. They are supported by Adobe Camera Raw, dcraw, and other editors. RW2 remains actively used today in Panasonic's Micro Four Thirds and full-frame Lumix cameras, making it important for enthusiast and professional workflows.

(Sony Raw 2). SR2 is an older Sony RAW format introduced before ARW became the standard. It was used by certain Sony DSLR models in the mid-2000s. Like other RAWs, it is TIFF-based, storing sensor data plus metadata. SR2 has been fully superseded by ARW, but legacy support exists in RAW converters. Today, SR2 is mainly encountered in archival contexts. Its role was transitional in Sony's shift from Konica Minolta heritage to its Alpha system.

(Sony Raw File). SRF is another early Sony RAW format, used primarily in the company's first digital cameras. Like SR2, it was later replaced by ARW. SRF shares the same purpose—capturing minimally processed sensor data for maximum editing flexibility. It is rarely seen today except in archival workflows or legacy archives.

(Sigma Raw, Foveon). X3F is the RAW file format used by Sigma cameras equipped with Foveon sensors. Unlike Bayer sensors, Foveon sensors capture full color information at each photosite by stacking three photodiodes sensitive to red, green, and blue light. X3F files store this unique data, enabling very sharp color detail and distinct rendering. Sigma Photo Pro is the primary software for processing X3F, though support exists in some open-source tools. While niche, X3F highlights Sigma's alternative approach to image capture and is significant in digital photography history.

(Encapsulated PostScript). EPS was created by Adobe in 1987 as a container for PostScript-based graphics. It became the standard for exchanging illustrations between applications in the print industry. EPS can contain vector shapes, text, and bitmaps but lacks modern features like transparency. It has largely been replaced by PDF but remains common in publishing and academic workflows.

(PostScript). PS is a page description language developed by Adobe in 1982. It precisely defines text, vector graphics, and images for printers and displays. PostScript revolutionized desktop publishing and enabled device-independent printing. Though verbose and now mostly replaced by PDF, PS still underpins many archival and scientific document workflows.

(Photoshop Big). PSB is Adobe Photoshop's large document format, created to bypass the 2 GB size limit of PSD files. It supports dimensions up to 300,000 by 300,000 pixels and retains all PSD features. PSB is used in specialized industries like film matte painting, billboard design, and scientific imaging where extremely high resolution is required.

JSON (JavaScript Object Notation). Created and popularized in the early 2000s by Douglas Crockford, JSON was designed as a lightweight, language-independent data format that maps cleanly to JavaScript types. It replaced bulky XML in many web APIs because it’s easy to read, easy to parse, and trivial to generate. The formal definitions live in ECMA-404 and RFC 8259. JSON sticks to objects, arrays, strings, numbers, booleans, and null—no comments by design—and everything is Unicode (commonly UTF-8). It took off with AJAX-era web apps, then became the default for REST, microservices, and serverless functions. Today it’s everywhere: config files, telemetry payloads, NoSQL stores (MongoDB, CouchDB), search platforms (Elasticsearch), and cloud SDKs. The trade-offs: it’s verbose compared to binary formats, numbers are not typed beyond “number,” and comments are missing (people hack around this with JSON5 or separate .env files). Still, for interoperability and human readability, JSON is the web’s lingua franca.

(Portable Document Format). Widely used for exporting drawings to ensure universal readability and print fidelity. PDF preserves vector paths, text, and embedded images, making it ideal for sharing diagrams and illustrations. It is the preferred format for publishing or printing final drawings.

(Plain Text). TXT exports often store delimited spreadsheet data with custom separators. Universally compatible but requires user-specified parsing.

YAML (YAML Ain’t Markup Language). Proposed around 2001 by Clark Evans with co-authors Oren Ben-Kiki and Ingy döt Net, YAML set out to be a human-friendly data serialization format that reads like natural outlines rather than angle-bracket markup. It supports mappings, sequences, scalars, comments, anchors/aliases (for DRY configs), and rich types. YAML 1.2 aligns closely with JSON and is broadly a superset for common cases, but adds indentation-based structure that’s easy for humans to scan and easy to break with sloppy spacing. It rose to dominance in devops and cloud: Kubernetes manifests, GitHub Actions, GitLab CI, Ansible playbooks, Compose files, and countless app configs. The upsides are readability and expressive features; the gotchas are indentation sensitivity, surprising implicit typing in older parsers, and security concerns with unsafe loaders. Used carefully (UTF-8, spaces not tabs, strict schemas), YAML remains the go-to for declarative configuration at scale.

(MPEG-4 Part 14). Standardized by ISO/IEC in 2001, MP4 is a container built on the ISO Base Media File Format. It can hold video, audio, subtitles, and metadata. Adopted globally for its efficiency and compatibility, it supports codecs like H.264, HEVC, and AV1. Today it’s the dominant video format across the web, mobile, and broadcast.

(QuickTime Movie). Created by Apple in 1991, MOV was the foundation of QuickTime. It stores video, audio, and text in a flexible container. MOV directly influenced MP4, and Apple still uses it heavily in professional editing. While MP4 dominates distribution, MOV remains important in Mac and production workflows, especially with ProRes.

(Matroska). An open multimedia container introduced in 2002, inspired by Russian nesting dolls. It supports unlimited video, audio, and subtitle tracks, plus attachments. MKV is popular with archivists and enthusiasts for its flexibility and high-quality preservation. Widely supported by software like VLC, though hardware adoption is spottier than MP4.

(MPEG-4 Video). Apple’s variant of MP4 introduced in the mid-2000s, mainly used for iTunes media. M4V can carry DRM protection through Apple’s FairPlay. While nearly identical to MP4, the branding tied it to Apple ecosystems. Non-DRM M4V files usually play fine in MP4 players.

(Web Media). Launched by Google in 2010 as a royalty-free, open-source format optimized for the web. WebM uses Matroska under the hood, with VP8/VP9/AV1 video and Opus/Vorbis audio. It powers HTML5 video and is natively supported by most browsers. Used extensively on YouTube and web platforms.

(Audio Video Interleave). Developed by Microsoft in 1992 for Video for Windows. AVI is a simple container that can store video and audio streams but lacks modern features like efficient compression or advanced subtitles. Hugely popular in the 1990s, it persists mainly in legacy archives and conversion workflows.

(Flash MP4 Video). Adobe’s Flash-compatible MP4 container introduced in 2007. Designed to replace FLV for HD playback in Flash Player, supporting H.264 and AAC. It became common on streaming sites during Flash’s dominance. Now obsolete with Flash’s deprecation.

(Flash Video). Introduced by Macromedia in 2002, FLV powered the first era of web video, including YouTube’s early years. It was efficient for streaming but tied to Flash Player. With Flash’s end in 2020, FLV is obsolete, though many archives remain.

(Advanced Systems Format). Developed by Microsoft in the late 1990s, ASF was designed for streaming audio and video over networks. It often carried WMV or WMA streams. While pioneering, it was largely replaced by MP4 and adaptive streaming. Now legacy.

(Moving Picture Experts Group). Refers to MPEG-1 and MPEG-2 containers standardized in the 1990s. Used in CDs, VCDs, DVDs, and broadcast television. Though largely replaced, MPEG containers are still found in archival media and broadcasting.

(Moving Picture Experts Group video). A three-letter variant of .mpeg, popular on DOS and Windows where filename length was limited. Functionally identical, but common in legacy archives.

(3rd Generation Partnership Project). A lightweight container introduced in 2003 for video on 3G mobile phones. It carried low-resolution video (H.263, MPEG-4) with AMR or AAC audio. Once ubiquitous on feature phones, now obsolete in the smartphone era.

(Ogg Video). An open container from Xiph.Org designed to hold Theora video and Vorbis audio. Promoted as a royalty-free alternative to proprietary codecs in the 2000s. It saw limited adoption before WebM replaced it. Now mostly legacy but significant in open media history.

(Anime Music Video). A low-resolution format used in inexpensive Chinese MP4 players in the mid-2000s. It offered very small file sizes with basic MP3 audio. Obsolete, but notable for its role in budget media devices.

(Transport Stream). Standardized as part of MPEG-2 in the mid-1990s, TS was designed for transmitting audio and video over unreliable channels like broadcast or IPTV. It breaks streams into packets for error correction. Still used in DVB, ATSC, and live broadcasting, though consumers often convert TS to MP4 or MKV.

(MPEG-2 Transport Stream Blu-ray). A variant of TS used on Blu-ray discs and AVCHD camcorders. Supports multiple video and audio streams, including H.264 and Dolby/DTS. Still used for Blu-ray authoring and archival media.

(Animated Portable Network Graphics). Proposed by Mozilla in 2004, APNG adds full 24-bit color and alpha transparency animation to PNG. Though not an official part of the PNG spec, it gained support in Firefox, Safari, and later Chrome. Used for stickers and UI animations.

3FR (Hasselblad 3F RAW). 3FR is Hasselblad's proprietary RAW format introduced for its medium-format digital cameras. It is based on TIFF/EP and stores minimally processed sensor data with metadata. Hasselblad designed 3FR for maximum editing latitude in professional workflows. Files are typically converted to Hasselblad’s archival format, .fff, after capture. Today, 3FR is supported in Hasselblad Phocus software and major RAW editors like Lightroom and Capture One.

A (Archive or object files). The .a extension is most common in Unix-like systems where it represents static libraries or archive files created with 'ar'. These contain compiled object code used by linkers. Not an image format in the conventional sense, but in some imaging libraries .a may appear as temporary or bundled resource files. Still widely used in programming, less so in multimedia workflows.

AVCI (Advanced Video Coding Intra). AVCI refers to a class of H.264/AVC profiles (like AVC-Intra) designed for professional video capture. Used by Panasonic and others in broadcast cameras, AVCI stores each frame as an intra-frame, making editing smoother. Though not a standalone format, .avci files appear in production pipelines. It is still active in television workflows.

B (Binary file). The .b extension has historically denoted raw binary dumps or language-specific compiled code (like BASIC). In imaging, it can appear as generic raw pixel data dumps with no header, requiring manual interpretation. Rare in modern consumer use, but still seen in research and embedded systems.

BMP2. BMP2 refers to a variant of the Microsoft Bitmap format produced by ImageMagick or legacy systems, using the BMP v2 specification. It stores uncompressed or RLE-compressed raster images. Mostly of historical interest, as BMP3 and later are more common.

BMP3. Another ImageMagick-related variant of BMP, following the v3 Windows BMP header. It allows for more metadata and color depth options compared to BMP2. Rare outside of conversion workflows.

Canvas (ImageMagick internal). In ImageMagick, 'canvas:' is a pseudo-format for creating solid color images (e.g., canvas:white). It’s not a portable file format but a generator keyword. Used for quick testing or creating placeholder images.

Caption (ImageMagick pseudo-format). 'caption:' creates images of text rendered into a bitmap using specified fonts. Useful for automated watermarking, labels, or text overlays. Like 'canvas', it's not a standalone format but an internal generator.

CRW (Canon Raw). CRW is Canon’s original RAW format used in early PowerShot and EOS cameras before CR2. It was based on the CIFF specification (Camera Image File Format). Superseded by CR2 in the mid-2000s, but still supported by converters like dcraw. It represents Canon’s first step into digital RAW imaging.

CUBE (3D LUT format). The .cube extension denotes LUT (Lookup Table) files used in color grading. Developed by IRIDAS (later acquired by Adobe), .cube files map input colors to output colors, allowing complex grading effects. They’re widely used in video editing, VFX, and color pipelines. Not images themselves, but essential to visual workflows.

CUT (Dr. Halo format). CUT was a raster graphics format used by Dr. Halo paint software in the 1980s and 1990s. It stored indexed-color images along with an optional palette file (.PAL). Obsolete today but occasionally encountered in retro computing archives.

DATA. A generic extension for binary or textual dumps. In imaging contexts, .data files may hold raw pixel dumps or serialized information for analysis. Not a standard, but context-specific.

DCM (DICOM Medical Images). DCM stands for Digital Imaging and Communications in Medicine. Developed by NEMA and ACR in the 1980s, DICOM standardizes the storage and transfer of medical images like CT, MRI, and ultrasound. DCM files embed both pixel data and rich metadata (patient info, scan parameters). Still the cornerstone of medical imaging worldwide.

DCR (Kodak RAW). DCR is a proprietary RAW format used by Kodak digital cameras. It stores sensor data in a TIFF/EP structure. Supported by Kodak software and third-party converters. Obsolete after Kodak left the camera market, but still present in archives.

dcraw (utility source). dcraw is not a format but a famous open-source tool created by Dave Coffin to decode RAW camera files. Sometimes files are mislabeled with .dcraw to denote raw dumps. dcraw itself is discontinued but underpins many open-source libraries.

DCX (ZSoft Multi-page PCX). DCX is an extension of the PCX format developed by ZSoft. It allows multiple PCX images in a single file, often used in fax software. Obsolete but still supported by conversion utilities.

DFONT (Mac OS Data Fork Font). Introduced with Mac OS X, .dfont stored fonts in the data fork of files rather than resource forks. While not an image format, .dfont files are part of system rendering pipelines. Later replaced by modern OpenType fonts.

FFF (Hasselblad Flexible File Format). FFF is Hasselblad’s archival RAW format. After initial capture in 3FR, files are converted to .fff for editing in Hasselblad Phocus. It preserves all sensor data and metadata. Still standard for Hasselblad digital workflows.

FILE. A generic extension used by some systems to denote unidentified or raw data. Not a standardized format; interpretation depends on context. In imaging archives, it may contain pixel dumps or metadata.

Fractal Image Format. Proposed in the 1990s by Iterated Systems, fractal compression promised extremely high compression ratios with resolution-independent decoding. Despite hype, it was computationally expensive and never gained traction. Rare curiosity today.

FTP (File Transfer Protocol pseudo-format). In ImageMagick and similar tools, 'ftp:' is a way to fetch images from an FTP server. Not a file format but a protocol handler. Useful in automated pipelines.

G (BRL-CAD Geometry). In BRL-CAD, a .g file stores geometry and attributes, often for defense or engineering modeling. Though not an image format, it is used in visualization workflows.

G3 (CCITT Group 3 Fax). G3 files use ITU-T T.4 standard for fax transmissions, compressing monochrome bitmaps efficiently. Widely used in the fax era, less so now, though legacy systems and archives still contain G3.

GIF87a. The original 1987 version of the Graphics Interchange Format introduced by CompuServe. It lacked support for animation and transparency, which were added in GIF89a. Now largely obsolete, but historically significant.

Gradient (ImageMagick pseudo-format). 'gradient:' generates smooth transitions between colors. Not a portable format but useful in testing and graphics generation pipelines.

Group 4 Fax. CCITT Group 4 is a fax image compression standard for monochrome documents. It achieves higher efficiency than Group 3. Still embedded in TIFF files for scanned documents.

GV (Graphviz DOT). The .gv extension is used for Graphviz graph descriptions, a text-based language for nodes and edges. While not an image format itself, Graphviz renders GV into diagrams (PNG, SVG, PDF). Still heavily used in software engineering and visualization.

HALD CLUT. A hald (hypercube) CLUT image encodes 3D color look-up tables as grids. Popular in ImageMagick for applying color grading effects. More a technique than a standalone format.

Histogram (ImageMagick pseudo-format). Produces an image representing the histogram of colors in another image. Not portable, but useful for analysis and diagnostics.

ICB (Targa ICB). A variant of the Truevision TGA format. Used in early video and graphics pipelines. Rare today, but still supported by conversion tools.

IIQ (Phase One Intelligent Image Quality). IIQ is the RAW format of Phase One medium-format cameras. It preserves full sensor data for maximum flexibility. Phase One Capture One software is the reference editor, though other tools also support IIQ. It remains central to professional medium-format workflows.

Inline (ImageMagick pseudo-format). 'inline:' embeds image data directly into text streams using Base64 encoding. Handy for embedding small images in scripts or configs.

JNX (Garmin BirdsEye). JNX is a raster map format used by Garmin GPS devices for BirdsEye satellite imagery. Proprietary, but supported by Garmin software and some open-source tools.

JP2 (JPEG 2000). JPEG 2000 was standardized by ISO/IEC in 2000 as a wavelet-based successor to JPEG. It supports lossy and lossless modes, higher bit depths, and better compression. Despite technical advantages, adoption was weak due to patents and slow encoding. It survives in niches like medical imaging, digital cinema, and archives.

JPM (JPEG 2000 Multi-layer). JPM is part of the JPEG 2000 family for compound images with multiple layers or mixed content. It was designed for scanned documents combining text and pictures. Rare outside of specialized workflows.

JPS (JPEG Stereo). JPS files store stereoscopic 3D images in side-by-side JPEG format. Popular with early 3D TVs and cameras, but faded as 3D consumer tech declined. Still viewable with 3D software.

K (raw data). A rare extension, sometimes used for raw pixel dumps or niche scientific formats. Not standardized.

K25 (Kodak RAW). K25 was Kodak’s RAW format for early digital cameras like the Kodak DC25. Based on TIFF, it preserved sensor data. Superseded by KDC and DCR. Now obsolete, but of archival interest.

Label (ImageMagick pseudo-format). 'label:' creates text labels rendered as bitmaps. Useful in automation and watermarks. Not a portable format.

MAC (MacPaint). MAC files were created by Apple’s MacPaint software in 1984. They stored 1-bit bitmap graphics for the original Macintosh. Historically important as one of the first GUI paint program formats. Now obsolete, viewable via converters.

MDC (Minolta RAW). MDC is an older Minolta RAW format before MRW. Obsolete after Minolta’s transition to Sony, but supported by dcraw and some converters.

MOS (Leaf RAW). MOS is the RAW format used by Leaf medium-format digital backs. Based on TIFF/EP, it preserves sensor data. Leaf was later acquired by Phase One, and MOS persists in archives of professional shoots.

MPO (Multi Picture Object). MPO is an extension of JPEG that allows multiple images in one file. Introduced by CIPA for stereoscopic 3D images and panoramas. Common in Fuji and Nintendo 3DS cameras. Still usable where 3D workflows exist.

MSL (Magick Scripting Language). A scripting format for ImageMagick to define batch image operations. Text-based, not a portable image format.

MVG (Magick Vector Graphics). ImageMagick’s own vector language, similar to SVG but proprietary. Used internally to describe vector drawings. Not portable beyond ImageMagick.

NRW (Nikon RAW). NRW is Nikon’s RAW format for compact cameras, introduced in the 2000s. Similar to NEF but simplified. Still supported in Nikon software and some editors.

NULL (ImageMagick pseudo-format). Acts as a sink or placeholder in pipelines. No image is written. Useful in scripting.

O (object file). Like .a, .o files are compiled object code in Unix-like systems. Sometimes appear in imaging builds. Not a portable image format.

PAM (Portable Arbitrary Map). Part of the Netpbm family, PAM generalizes PBM/PGM/PPM by allowing arbitrary tuples with a header describing depth and types. Introduced in 2002. Rare but flexible for experimental workflows.

Pango. In ImageMagick, 'pango:' renders text using the Pango layout engine (GTK). Supports complex scripts and Unicode. Pseudo-format, not portable.

Pattern (ImageMagick pseudo-format). 'pattern:' generates tiled test images or procedural patterns. Useful in development, not for interchange.

PES (Brother Embroidery Format). PES is used by Brother sewing and embroidery machines to encode stitch patterns. It stores instructions rather than pixels. Still actively used in textiles.

PFA (PostScript Font ASCII). A variant of Type 1 PostScript fonts where data is stored as ASCII text. Used in early font workflows. Replaced by OpenType.

PFB (PostScript Font Binary). The binary counterpart to PFA, storing Type 1 font programs compactly. Used in desktop publishing. Superseded by OpenType.

PIX (Alias/Wavefront). PIX is an image format used in the Alias/Wavefront graphics software of the 1990s. Obsolete but found in CGI/VFX archives.

PJPEG (Progressive JPEG). A variant of JPEG defined in the original standard. Progressive mode encodes images in scans that refine over time, improving perceived load speed. Supported widely, though not always default.

Plasma (ImageMagick pseudo-format). 'plasma:' generates random plasma fractals. Useful for textures or tests. Not a portable format.

PNG00 (specialized PNG). In ImageMagick, this denotes an output intent: PNG with no alpha channel. Rare outside of internal workflows.

PNG24. Refers to 24-bit RGB PNG images. Not an official separate format, but shorthand in tools for full-color PNG.

PNG32. Refers to 32-bit RGBA PNG with alpha channel. Common shorthand in software dialogs.

PNG48. Refers to 48-bit PNG (16 bits per channel). Used in scientific or high-fidelity imaging.

PNG64. Refers to 64-bit RGBA PNG (16 bits per channel). High-depth with transparency. Niche, but supported by spec.

PNG8. Refers to 8-bit indexed PNG (256 colors). Used for lightweight web graphics. Alternative to GIF.

PocketMod. A DIY printable booklet format combining multiple pages into one sheet for folding. Not a digital image format per se, but used in graphic arts.

PTIF (Pyramid TIFF). A tiled, multi-resolution TIFF used in deep zoom viewers. Popular in medical imaging and GIS. Still in active use.

PWP (Photoworks). PWP was a proprietary raster format by Seattle FilmWorks/PhotoWorks in the 1990s. Rare today, mainly archival.

QOI (Quite OK Image). Created by Dominic Szablewski in 2021, QOI is a lossless image format emphasizing simplicity and speed over maximum compression. It uses run-length and simple indexing. Popular in programming demos, niche adoption compared to PNG.

Radial Gradient (ImageMagick pseudo-format). Generates radial color blends procedurally. Useful in testing or texture generation.

RAW (generic). .raw often denotes unprocessed binary dumps of sensor or pixel data with no header. Interpretation depends on context (width, height, depth must be known). Used in research, graphics, and camera pipelines.

RGB565. A raw pixel format with 16 bits per pixel: 5 bits red, 6 green, 5 blue. Common in embedded systems, LCDs, and game consoles. Not a standalone file format, but widely referenced.

RLA (Wavefront Raster). Created by Wavefront Technologies in the 1980s for visual effects. Supported multiple channels and high dynamic range. Obsolete, replaced by EXR.

RLE (Run-Length Encoded Bitmap). A generic term and also a specific format in Windows BMP. Compresses repeating pixels efficiently. Used historically in faxes, icons, and games.

RWL (Leica RAW). RWL is Leica’s proprietary RAW format used in its digital cameras. Based on TIFF/EP, similar to DNG. Supported by Leica software and major editors.

Screenshot. A generic label for files generated by screen capture utilities. Extensions vary by OS (png, jpg, bmp). Not a defined format.

SFW (Seattle FilmWorks). Proprietary raster format from Seattle FilmWorks photo processing. Obsolete, but legacy files exist.

SGI (Silicon Graphics Image). Developed by Silicon Graphics for its IRIX workstations. Supports run-length compression, 8–32 bit channels, and simple headers. Popular in CGI pipelines of the 1990s. Still supported by many converters.

SRW (Samsung RAW). SRW is Samsung’s RAW camera format, based on TIFF/EP. Supported in Samsung’s software and Adobe Camera Raw. Obsolete since Samsung left the camera market.

Stegano. Refers to steganographic image files—images with hidden data embedded inside. Not a standard extension, but used in research and hacking contexts.

STI (Microsoft Clip Gallery). STI files stored clipart collections in Microsoft Office. Obsolete since Office dropped clip art libraries.

Tile (ImageMagick pseudo-format). 'tile:' creates images by tiling an input across an output canvas. Useful in pattern generation.

TIM (PlayStation TIM). TIM was Sony PlayStation’s native texture format in the 1990s. It supported palettes and multiple bit depths. Common in game asset ripping. Obsolete but relevant in retro game preservation.

TM2 (PlayStation 2 TIM2). TIM2 succeeded TIM as Sony PS2’s texture format, supporting higher color depth and compression. Used in game development, still found in modding.

VDA (Targa Bitmap). A variant of the TGA (Truevision) image format. Used in early graphics. Obsolete, but supported in converters.

VID (Generic Video). A generic extension used in DOS-era software for raw video streams. Not standardized. Requires context to interpret.

WMF (Windows Metafile). Developed by Microsoft in the early 1990s, WMF stores vector and bitmap drawing commands. Superseded by EMF and later formats. Still supported in Office for legacy graphics.

XBM (X11 Bitmap). ASCII-based bitmap format used in X Window System for monochrome icons and cursors. Simple, human-readable C arrays. Still supported but largely replaced by PNG.

XC (ImageMagick pseudo-format). 'xc:' creates a single pixel of a specified color, often used for debugging or as a base canvas.

XCF (eXperimental Computing Facility). XCF is the native format of GIMP (GNU Image Manipulation Program). It preserves layers, masks, channels, and paths. Not intended as an interchange format but for GIMP editing. Superseded by exporting to PNG, JPEG, or TIFF for delivery.

XPM (X PixMap). ASCII-based color image format for the X Window System. Designed to store small icons and bitmaps in C source code. Still used in legacy X applications.

XWD (X Window Dump). XWD files store raw pixel dumps from X Window screens, along with headers. Used for screenshots in Unix systems. Still supported but mostly obsolete.

Y (Berkeley YACC grammar / image pseudo-extension). .y is normally for YACC grammar files, but in imaging toolkits may denote experimental formats. Extremely context-dependent and not standardized.

(MPEG-1/2 Audio Layer III). Developed in the early 1990s by the Fraunhofer Institute in Germany, MP3 became the most recognizable digital audio format. Its lossy compression discards inaudible frequencies using psychoacoustic models, reducing file size dramatically while preserving acceptable quality. It powered the rise of portable music players, Napster-era file sharing, and digital downloads. While technically surpassed by newer codecs like AAC and Opus, MP3 remains ubiquitous due to universal support across hardware, software, and streaming.

(Advanced Audio Coding). Created in the late 1990s by a consortium including Fraunhofer, AT&T, Sony, and Dolby, AAC was designed as a successor to MP3 with more efficient compression. It supports multichannel audio, higher sample rates, and better quality at lower bitrates. AAC is the standard for iTunes, YouTube, DAB+ digital radio, and many streaming services. Despite being newer, it has become nearly as universally supported as MP3, especially on mobile and web platforms.

(MPEG-4 Audio). M4A is essentially AAC (or sometimes ALAC) audio stored inside an MPEG-4 container. Apple popularized the extension in iTunes, where it denoted non-DRM music files compared to .m4p (protected). M4A supports album art, metadata, and efficient encoding. Though technically identical to AAC in MP4, M4A became shorthand for high-quality Apple-distributed audio and is still common in Apple Music ecosystems.

(Ogg Vorbis). Ogg is the container developed by the Xiph.Org Foundation, with Vorbis as the common lossy codec inside. Launched in the early 2000s as a free, open-source alternative to MP3 and AAC, Vorbis achieved comparable or better quality at similar bitrates. It was embraced by open-source advocates, games, and some streaming platforms (like Spotify early on). While its prominence has faded in favor of Opus, Vorbis remains relevant in legacy applications and open media archives.

(Opus Interactive Audio Codec). Standardized by the IETF in 2012, Opus combines SILK (speech) and CELT (music) technologies into a highly adaptive codec. It supports ultra-low latency, wide dynamic range, and bitrates from narrowband voice to full-bandwidth stereo. Opus was designed for internet applications—VoIP, WebRTC, live streaming—and is now the default audio codec in browsers and platforms like Discord and Zoom. It outperforms MP3 and AAC in efficiency and flexibility, making it the modern standard for real-time communication.

(Windows Media Audio). Developed by Microsoft in 1999, WMA was part of the Windows Media framework. It was created to compete with MP3, with variants like WMA Pro for high fidelity and WMA Lossless. WMA saw heavy use in Windows PCs, Zune players, and DRM-protected online music stores. However, its closed nature and poor cross-platform support limited adoption. Today, WMA lingers in legacy libraries but is effectively obsolete compared to MP3, AAC, and FLAC.

(Free Lossless Audio Codec). Introduced in 2001 by Josh Coalson, FLAC became the dominant open-source lossless audio format. It compresses audio without losing any data, typically reducing file size by 30–60% while retaining perfect fidelity. FLAC supports rich metadata, album art, and error resilience. It’s the standard for audiophile downloads, archives, and digital music collections. Unlike ALAC, FLAC is free of patents and widely supported across platforms and devices.

(WavPack). Created by David Bryant in the late 1990s, WavPack is a hybrid audio codec supporting lossless, lossy, and a unique hybrid mode that combines both. Its flexibility allows users to save space while keeping a correction file for full restoration. Although less popular than FLAC, it has a dedicated following in audiophile circles and open-source communities. Supported by many players and tools, WavPack remains relevant for users who value versatility.

(Waveform Audio File Format). Co-developed by Microsoft and IBM in 1991, WAV is a container format for uncompressed PCM audio. As a RIFF-based format, it stores raw samples plus metadata like bit depth and channels. WAV became the standard for professional audio recording and editing because it preserves full fidelity and is universally supported. Its drawback is large file size. Today, WAV is used in studios, DAWs, and archival storage, while compressed formats serve distribution.

(Audio Interchange File Format). Developed by Apple in 1988, AIFF is essentially Apple’s equivalent to WAV, based on the Electronic Arts IFF structure. It stores uncompressed PCM audio and supports metadata like loop points and markers, making it popular in music production on Macs. AIFF saw heavy use in professional audio before cross-platform WAV took over. It remains supported in macOS and audio workstations but is less common outside Apple ecosystems.

(Pulse-Code Modulation). PCM is the raw representation of audio as sampled amplitude values, the foundation of digital audio. Not tied to a specific extension, .pcm files are often raw dumps of sample data without headers. PCM was standardized in the 1960s for telephony and underpins CDs (44.1 kHz, 16-bit). It is still used in professional workflows where raw, uncompressed fidelity is required. Containers like WAV or AIFF typically wrap PCM for portability.

(Adaptive Multi-Rate). Standardized by 3GPP in 1999, AMR is a speech codec optimized for mobile phones. It dynamically adjusts bitrate for efficiency on variable networks. AMR was widely used for voice calls and stored in .amr files for recordings on early mobile phones. Still used in telephony and VoIP, though largely replaced by Opus and wideband codecs for internet communication.

(Audio Unix). AU was introduced by Sun Microsystems in the late 1980s for Unix systems. It stored PCM or compressed audio with a simple header. AU became common in early internet and academic environments, especially with the 'u-law' encoding. Now obsolete, it survives mainly in retro software and archives.

(Audio Codec 3). Developed by Dolby Laboratories in 1991, AC-3—also known as Dolby Digital—was designed for cinema and home theater. It provides up to 5.1 channels of surround sound with efficient lossy compression. AC-3 became standard on DVDs, HDTV broadcasts, and many theaters. Though newer codecs like Dolby Digital Plus and DTS-HD exist, AC-3 remains entrenched in consumer electronics and legacy media.

(Digital Theater Systems). DTS was founded in 1993 as a competitor to Dolby Digital, debuting with Jurassic Park. Like AC-3, DTS provides multichannel surround sound but at higher bitrates, favoring quality over efficiency. DTS became a staple in DVDs, Blu-rays, and high-end audio systems. While newer immersive formats like DTS:X exist, the original DTS core remains a key part of home theater and cinema playback.

(HyperText Markup Language). In spreadsheets, HTML export encodes tables using table elements. Supported since the 1990s for publishing spreadsheets to the web. Still common for quick exports, though XLSX and CSV are preferred for data workflows.

(Extensible HyperText Markup Language). A reformulation of HTML using XML syntax, standardized by W3C in 2000. It enforced stricter rules, like closed tags and case sensitivity. Intended to merge HTML’s ubiquity with XML’s rigor. It saw limited adoption but influenced cleaner coding practices. Modern development shifted back to HTML5, though XHTML remains in archives and some CMS templates.

(HyperText Markup). Same as HTML, just the shorter three-letter extension due to DOS-era limits. Used interchangeably with .html for spreadsheet web exports.

(Document). Microsoft’s binary word processing format introduced in 1983 with Word for MS-DOS. It dominated office environments throughout the 1990s and 2000s. DOC stored text, formatting, macros, and embedded objects in a proprietary structure. Superseded by DOCX in 2007 with Office Open XML, but DOC remains heavily supported for backward compatibility.

(Writer’s Word Processor). A proprietary format from Microsoft Works, a lightweight office suite launched in 1987. WPS files contained text, basic formatting, and tables. Popular among home users until Works was discontinued in 2009. Today, WPS files survive in old archives but are less supported outside conversion tools.

(Flat ODT). An XML-based variant of OpenDocument Text (ODT), stored in a single flat XML file instead of a ZIP container. Defined in the OASIS OpenDocument standard. Easier to parse or version-control than zipped ODT. Still supported in LibreOffice and OpenOffice.

(OpenDocument Text). The main word processing format of the OASIS OpenDocument standard, adopted by LibreOffice, Apache OpenOffice, and others since 2005. ODT is a ZIP container holding XML and media. Chosen by governments and institutions for openness and long-term accessibility. Competes with Microsoft’s DOCX.

(Extensible Markup Language). Used as the underlying representation for many drawing formats in the early 2000s, especially StarOffice and early OpenOffice.org. XML-based drawings stored shapes, styles, and layers in plain text for interchange and parsing. Largely superseded by packaged formats like ODG but still supported for compatibility.

(Rich Text Format). Introduced by Microsoft in 1987 as a cross-platform text document format. It encodes styled text using human-readable control words. RTF was designed to allow interchange between word processors before DOC or DOCX dominated. Now mostly legacy, but still supported by most editors for simple formatted text interchange.

(Comma-Separated Values). Encodes tabular data as text with commas. Universally supported. Still dominant for data interchange despite ambiguities in quoting and separators.

(Tab-Separated Values). Same as CSV but with tabs as delimiters. Favored when data fields contain commas. Popular in research and databases.

(Tabular Text). Alternative extension for tab-delimited files, functionally the same as TSV. Common in exports from statistical software.

(OpenDocument Text Template). Part of OASIS OpenDocument, OTT files define reusable word processing templates for LibreOffice or OpenOffice. They store styles, layouts, and placeholder text for consistent document creation. Supported in open office suites and by some converters.

(Office Open XML Document). Standardized as ECMA-376 and ISO/IEC 29500 in 2006, DOCX became Microsoft Word’s default format. It’s a ZIP container holding XML and media. Introduced to replace DOC with a more open, transparent structure. Now the dominant word processing format worldwide.

(Office Open XML Template). A DOCX-based template format for Microsoft Word. DOTX files contain pre-defined layouts, styles, and boilerplate text. Used for consistent document creation in businesses and organizations. Macro-free variant of DOTM.

(Office Open XML Macro-Enabled Document). A DOCX variant introduced with Office 2007 that supports embedded VBA macros. Useful for automating tasks, but carries security risks. Still used in enterprise workflows that rely on automation.

(AbiWord). ABW is the native document format of AbiWord, an open-source word processor first released in 1998. It stores text, styles, and images in an XML-based structure. ABW was designed to be lightweight and open. While AbiWord’s popularity has declined, ABW files are still supported in conversion tools.

(Zipped AbiWord). A compressed version of ABW that bundles XML and media resources in a ZIP container. Introduced to reduce file size and package images cleanly. Recognized by AbiWord and compatible converters.

(ClarisWorks/AppleWorks). CWK is a document format from ClarisWorks (later AppleWorks), Apple’s office suite from 1991 until its discontinuation in 2007. CWK could contain word processing, spreadsheets, and drawings. Proprietary and now obsolete, though converters exist for archival access.

(MacWrite). MW files belong to MacWrite, one of the first word processors for the Macintosh, released in 1984. They stored styled text and simple formatting. Historically significant as an early GUI word processor, but obsolete since the 1990s.

(MacWrite II/Claris MacWrite). MCW was used by later versions of MacWrite in the late 1980s and early 1990s. Similar to MW, it offered improved formatting and compatibility. Now legacy, supported only by conversion utilities.

(Mariner Write Document). MWD files are from Mariner Write, a lightweight Mac word processor still maintained. They store text and styles, functioning as an alternative to Word or Pages for macOS users.

(WriteNow). WriteNow was a fast, efficient word processor for NeXTSTEP and Macintosh in the late 1980s. WN files contained styled text and were highly regarded for speed. Obsolete after Apple discontinued NeXTSTEP-related software.

(Nick’s eXtended D). Rare, proprietary word processor format from obscure software. Likely tied to regional or experimental tools. Very limited documentation, now effectively abandoned.

(Lotus Word Pro). LWP was Lotus Word Pro’s native format, introduced in 1992 as part of Lotus SmartSuite. It stored word processing documents with styles and graphics. Declined after IBM acquired Lotus. Obsolete but convertible with tools like LibreOffice.

(Hangul Word Processor). HWP is South Korea’s national document format, created by Hancom in the 1990s. It supports Hangul text, styles, and embedded content. Still widely used in Korea, supported by government agencies. Proprietary, but some specifications have been published.

(BroadBand eBook / Sony Reader). LRF was Sony’s proprietary ebook format used in early Sony Reader devices before EPUB. It stored reflowable text, images, and metadata. Obsolete today, replaced by EPUB and PDF.

(FictionBook 2.0). An open XML-based ebook format developed in Russia in the early 2000s. FB2 encodes book structure (titles, epigraphs, metadata) in semantic markup rather than styling. Supported by many ebook readers in Eastern Europe. Still used by enthusiasts and archives.

(ZIP Archive). Invented by Phil Katz in 1989 for PKZIP, ZIP is a general-purpose compressed container. In document contexts, formats like DOCX, ODT, and EPUB are actually ZIP archives containing XML and media. ZIP remains universal for bundling and sharing documents.

(Palm Database). PDB was used by Palm OS devices for ebooks, applications, and databases in the late 1990s and 2000s. For documents, PDB often contained text formatted for small screens. Obsolete after Palm’s decline but preserved in archives.

(Apple Pages). Pages documents are Apple’s proprietary word processing format introduced in 2005 with iWork. Based on a package of XML, binary, and images, .pages files support styled text, layouts, and graphics. Still Apple’s standard for macOS and iOS, though exports to DOCX/PDF are common for sharing.

(Lotus 1-2-3 Worksheet 1). A spreadsheet format from the early 1980s. Once dominant in business before Excel overtook Lotus. Now legacy but convertible.

(Lotus/Works Spreadsheet). Early spreadsheet files from Lotus or Microsoft Works. Contained simple tables and formulas. Obsolete today.

(Quattro Pro Spreadsheet). Corel Quattro Pro’s format from the 1990s. Competed with Lotus and Excel. Rare today but still supported by Corel.

(Excel Binary Spreadsheet). Microsoft’s proprietary binary format introduced in 1987. Reigned until replaced by XLSX in 2007. Still heavily supported for legacy data.

(Excel Workspace). Saved workspace layouts in older Excel versions. Rare but supported for compatibility.

(Excel Chart). Used in early Excel to store charts separately. Deprecated in favor of embedding charts directly.

(Excel Macro). Early Excel macro format introduced in 1992. Superseded by VBA macros. Still supported for backward compatibility.

(Excel Template). Binary template format used before Office 2007. Replaced by XLTX/XLTM.

(StarOffice Calc). Early XML-based spreadsheet format from StarOffice/OpenOffice before ODS. Now obsolete.

(StarOffice Calc Template). Template counterpart to SXC. Superseded by OTS.

(Apache Parquet). A modern columnar storage format for big data introduced in 2013. Optimized for analytics and cloud warehouses. Used in Spark, Hadoop, and beyond.

(Gnumeric Spreadsheet). Native format of the open-source Gnumeric spreadsheet editor. XML-based. Still maintained but niche.

(Gnumeric XML). Alternative XML-based format used by Gnumeric for debugging or interchange. Rare outside of Gnumeric.

(Excel Binary Workbook). Introduced in Office 2007, XLSB compresses binary workbook data for faster performance with large datasets. Supported in modern Excel.

(Apple Numbers). Apple’s spreadsheet format, part of iWork since 2007. Stores tables and formulas in an XML-based bundle. Still Apple’s standard but exports to XLSX for sharing.

(Kingsoft Presentation). The native presentation format of WPS Office (formerly Kingsoft Office), popular in China and Asia. Equivalent to PPTX. Still actively supported in WPS Office.

(Kingsoft Presentation Template). The template format of WPS Office Presentations. Stores layouts and themes for reuse. Equivalent to POTX.

(WordPerfect Graphics). A vector graphics format developed by Corel for WordPerfect Office. Common in the 1990s for illustrations and clipart. Now legacy, but still convertible in LibreOffice.

(Visio XML Drawing). Microsoft Visio’s XML-based diagram format introduced in 2003. It stores shapes, connections, and metadata. Superseded by VSDX in 2013 but still supported for legacy diagrams.

(Visio Drawing). Microsoft Visio’s proprietary binary format from the 1990s to 2013. Used heavily in enterprises for flowcharts, network diagrams, and engineering drawings. Replaced by VSDX but still widely encountered in archives.

(Visio Macro-Enabled Drawing). Introduced in Visio 2013, VSDM is based on Open Packaging Conventions with XML inside. Supports macros for automation. Still actively used in Visio workflows.

(Visio Drawing XML). The current default Visio format since 2013. It’s a zipped XML-based container replacing both VSD and VDX. Actively supported in Microsoft Visio and enterprise workflows.

(Microsoft Publisher). A desktop publishing format introduced in 1991. PUB files store text, graphics, and layout for flyers, brochures, and small-scale print work. Proprietary to Microsoft Publisher, still used in small business settings but less popular than PDF for sharing.

(CorelDRAW). Corel’s flagship vector graphics format introduced in 1989. CDR files store vector illustrations, text, and effects. Still the standard for CorelDRAW users and actively maintained. Competes with Adobe Illustrator’s AI format.

(Corel Presentation Exchange). A Corel format introduced in the 1990s for exchanging vector graphics and previews between Corel applications. It supported thumbnails and embedded resources. Now mostly obsolete, but still convertible in CorelDRAW and LibreOffice.

(Data Interchange Format). Created in the early 1980s for Visicalc, DIF encodes spreadsheets in plain text with control keywords. Its simplicity made it portable between early spreadsheet programs like Lotus 1-2-3 and Excel. Rare today, but still recognized by LibreOffice and conversion tools.

(Flat ODS). An XML-only, uncompressed form of OpenDocument Spreadsheet (ODS). Easier to version-control or debug than zipped ODS. Defined in the OASIS OpenDocument standard. Still supported in LibreOffice.

(OpenDocument Spreadsheet). The standard spreadsheet format of OASIS OpenDocument, introduced in 2005. A zipped container of XML and resources. Used by LibreOffice, Apache OpenOffice, and adopted by governments seeking open standards. Competes with Microsoft Excel formats.

(Excel Backup). XLK files are created by Excel as backup copies of spreadsheets. Contain the same data as XLS but with an alternate extension. Used mainly for recovery.

(Kingsoft Spreadsheets). ET is the spreadsheet format of Kingsoft’s WPS Office, an alternative office suite popular in Asia. Equivalent to XLSX. Still actively used.

(Kingsoft Spreadsheet Template). The template format for WPS Spreadsheets, equivalent to XLTX. Stores reusable layouts and formulas.

(Symbolic Link). A text-based spreadsheet interchange format created by Microsoft in the early 1980s. Uses delimited ASCII codes. Supported by Lotus 1-2-3, Excel, and others. Rare today, but important historically.

(Symbolic Link, alt). Another extension for the same SYLK spreadsheet format. Recognized by Excel. Legacy but still supported.

(Database File). Originally from dBASE II (1980s), DBF became a common format for storing tabular data with field types. Widely used in xBase languages and GIS. Supported by Excel, LibreOffice, and ESRI ArcGIS. Still present in legacy workflows.

(OpenDocument Spreadsheet Template). Template format in the OASIS standard. Used for reusable spreadsheet designs in LibreOffice/OpenOffice.

(Office Open XML Spreadsheet). Introduced with Office 2007, standardized as ISO/IEC 29500. XLSX is a zipped XML-based successor to XLS. It is now the dominant spreadsheet format worldwide.

(Office Open XML Macro-Enabled Spreadsheet). Like XLSX but allows embedded VBA macros. Introduced with Office 2007. Widely used in business automation workflows.

(Office Open XML Template). Template format for Excel introduced in Office 2007. Stores reusable layouts, styles, and formulas. Macro-free counterpart to XLTM.

(Office Open XML Macro-Enabled Template). Excel template format supporting VBA macros. Used for automated spreadsheets requiring reusable structures.

(PowerPoint Presentation). Microsoft’s binary slideshow format introduced in 1987 with the first version of PowerPoint. It stores slides with text, graphics, transitions, and embedded media. PPT dominated business and education presentations through the 1990s and early 2000s. Superseded by PPTX in 2007 but still supported for legacy compatibility.

(PowerPoint Show). A variant of PPT designed to launch directly into slideshow mode instead of edit mode. Common for distributing final presentations. Also replaced by PPSX in Office 2007 but still readable.

(PowerPoint Template). Microsoft’s template format for slideshows before Office Open XML. POT files stored slide layouts, themes, and placeholders for reuse. Replaced by POTX in 2007 but still convertible.

(Flat ODP). An XML-only, uncompressed variant of the OpenDocument Presentation format. Easier to parse and version-control than the zipped ODP. Supported by LibreOffice and Apache OpenOffice.

(OpenDocument Presentation). Part of the OASIS OpenDocument standard introduced in 2005. ODP is a zipped XML container for slides, styles, and media. The default for LibreOffice and OpenOffice Impress. Adopted in government and institutional contexts as an open alternative to PowerPoint formats.

(OpenDocument Presentation Template). The template format for ODP, storing slide layouts and themes for reuse. Standard in LibreOffice and OpenOffice Impress.

(PowerPoint Open XML Presentation). Introduced with Office 2007, PPTX is the zipped XML successor to PPT. Standardized as ECMA-376 and ISO/IEC 29500. It’s now the default PowerPoint format worldwide.

(PowerPoint Open XML Show). A PPTX variant that opens directly in slideshow mode. Used for distributing final decks. Still widely supported in modern Office.

(PowerPoint Open XML Macro-Enabled Template). A macro-enabled version of POTX introduced in Office 2007. Stores VBA macros along with layouts. Useful for automated or interactive presentations but carries security risks.

(PowerPoint Open XML Macro-Enabled Presentation). Macro-enabled counterpart to PPTX. Introduced in Office 2007. Common in enterprises where automation or interactive elements are embedded in slides.

(OpenDocument Drawing Template). Part of the OASIS OpenDocument standard introduced in 2005. OTG files define reusable drawing templates for LibreOffice and OpenOffice Draw. They store shapes, styles, and layout settings for consistent design across documents.