File extensions

A multimedia container from 3GPP, designed for mobile-era phones and low-bitrate clips.

An open-source archive format known for high compression ratios via LZMA2. Typically smaller than ZIP for the same payload.

MP3's successor — higher audio quality at the same bitrate, and the default codec on YouTube, iTunes Store, and digital broadcasting.

Apple's uncompressed audio format, dating back to the original Macintosh. Still a workhorse in music production.

The distribution package for Android apps. Internally a ZIP archive holding DEX bytecode, resources, and a manifest.

A styled subtitle format that became the de-facto standard in anime fansubs and VOCALOID MVs. Descends from the original SSA and supports rich typography.

Microsoft's original video container, heavily used in the Windows 98 era and still common on older camcorders and archival footage.

A next-generation image format built on the AV1 codec. Smaller files than WebP with support for transparency, HDR, and animation.

A Windows batch script run by the Command Prompt. Double-clicking executes the commands inside — and therefore can do anything a user can.

A catch-all extension for raw binary data — firmware images, disk images, ROMs, memory dumps, and so on.

The uncompressed bitmap format that originated on Windows. Simple to parse and fast to render, but produces huge files.

A Burrows-Wheeler compression format. Denser than gzip but slower; xz and 7-Zip have largely overtaken it in modern Linux distributions.

C language source from 1972. Foundation of the Linux kernel, all major databases, and countless system programs.

Windows' internal archive format. Still used to deliver drivers, Windows Update payloads, and MSI package contents.

The RAR-backed sibling of CBZ. Common in Western comic communities for years, where WinRAR tooling is ubiquitous.

A ZIP-based container for comics and manga. Just numbered image files inside a ZIP — popular for doujinshi, scanned manga, and self-hosted comic libraries.

Microsoft's help file format — HTML plus assets compressed with LZX. Widely used for online help in Windows software since 1998. Still actively distributed in China, Japan, and Korea.

C++ source. Still dominant in operating systems, game engines, finance, and embedded work where performance matters.

The styling language for the web. Paired with HTML it controls colour, layout, animations, and media queries.

A plain-text tabular format with comma-separated fields. The lowest-common-denominator for exchanging tables between spreadsheets, databases, and scripts.

A catch-all extension meaning 'some kind of data'. Game saves, email TNEF, app logs — all hide behind `.dat`.

The package format for Debian-based Linux distributions (Ubuntu, Mint, etc.). Installs, upgrades, and removes software via dpkg / apt.

A shared library on Windows. Loaded by `.exe` processes to expose functions. DLLs are never run on their own — always loaded into a host.

macOS disk image format. The default for distributing apps — double-click to mount, drag the `.app` to Applications to install.

The pre-2007 binary Word format (Compound File Binary). Still circulates in government and SMB workflows and carries a high malware-delivery risk because of embedded macros.

The default Word document format since Word 2007. Under the hood it is a ZIP package of XML and media — portable enough that most apps can open it.

A file of environment variables loaded at app startup. The `.env` convention is universal in modern development for API keys and DB URLs.

A vector image in PostScript. Still common in print shops and older design pipelines for delivering logos and illustrations.

The IDPF / W3C standard for e-books. Under the hood it is XHTML + CSS + metadata inside a ZIP — designed for reflowable text.

A native Windows executable. Double-clicking launches the program. Disguised EXEs are one of the most common malware delivery paths.

Lossless audio compression that reduces CD-quality recordings to roughly half the size of WAV. The de-facto choice for music archival.

The video format built for Adobe Flash. Ruled web video from early YouTube through the mid-2010s; legacy after Flash's end-of-life.

A lossless raster format with a 256-colour palette and limited animation support. Still ubiquitous on social feeds and chat reactions.

Source for Google's Go language. Known for lightweight goroutine concurrency and statically-linked single-binary output.

A gzip-compressed single file. Combined with tar it forms `.tar.gz`, the most common Linux distribution archive.

A C or C++ header file. Declares types, function prototypes, and macros pulled into other sources via `#include`.

The default image format on iPhone cameras. Roughly half the size of JPEG at similar quality, but can be awkward to open outside of Apple platforms.

The source of a web page. A browser renders it; a text editor shows you the markup underneath.

The native Windows icon format. A single file can hold multiple resolutions and colour depths — still the default for desktop icons and legacy web favicons.

A classic key-value configuration format. Still common in Windows apps and legacy Unix tools for profiles and settings.

The distribution package for iOS apps. A ZIP containing the `.app` bundle, metadata, and a provisioning profile.

A bit-for-bit image of a CD/DVD/Blu-ray. Used for OS installers, recovery media, and backups.

Source for the Java language. Compiles to `.class` bytecode that runs on the JVM.

A lossy compression format optimised for photographs — the default on smartphone cameras and web galleries. `.jpg` and `.jpeg` are identical; the three-letter form is a DOS-era holdover.

Source for the language that runs the web — in browsers and on servers (Node.js, Bun, Deno). Central to interactive UIs and modern tooling.

A lightweight data-interchange format. The de-facto standard for config files, API payloads, and database dumps.

The JPEG committee's 2022 next-generation image format. Losslessly transcodes existing JPEGs and supports HDR, wide gamut, and animation. Browser support is still uneven.

The native format for Apple's Keynote presentation app. Known for smoother transitions and cleaner typography than PowerPoint.

JetBrains' JVM language. Google's preferred language for Android and a more concise alternative to Java on the JVM.

A Japanese archive format released in 1988 by Haruyasu Yoshizaki. Ruled Japanese PC-98 and Windows 3.1 file distribution before ZIP took over. Rarely seen outside Japan; `.lha` and `.lzh` share the same bytes.

Runtime text output from apps and servers. The first place incident responders and admins look when something goes wrong.

AAC or ALAC audio wrapped in an MP4 container. Born from iTunes and best supported inside the Apple ecosystem.

Markdown source. A lightweight markup language used by GitHub READMEs, static site generators, and most technical blogs.

A single-file web page: HTML, images, and CSS bundled as a MIME multipart message. Born with Internet Explorer and still common in Chinese enterprise software and some government portals.

An open container that can bundle multiple audio tracks, subtitle streams, and chapter metadata — popular for anime rips and archival recordings.

The early Amazon Kindle e-book format. Amazon has since moved on to AZW3 and KFX; MOBI is legacy.

Apple's QuickTime container, widely produced by iPhone screen recordings and iMovie exports. Structurally similar to MP4, so conversions are usually lossless.

The de-facto standard for music distribution for over 25 years. Playable on virtually anything with a speaker.

The MPEG-4 container format that bundles video, audio, and subtitles. It is the de-facto universal video format — iPhones, Android, YouTube, everywhere.

The standard Windows installer container. Holds install, upgrade, repair, and uninstall instructions.

The native format for Apple's Numbers spreadsheet. Each sheet is a freeform canvas hosting multiple tables and charts.

The ISO OpenDocument presentation format. Native to LibreOffice Impress and convertible to/from pptx.

The ISO OpenDocument spreadsheet format. Native to LibreOffice Calc and broadly interoperable with xlsx.

The ISO-standardised open document format. Native to LibreOffice and OpenOffice, and broadly interoperable with docx.

Xiph.Org's open media container. Hosts Vorbis (audio), Theora (video), or Opus (audio) streams — royalty-free and common in open-source pipelines.

The successor font format co-developed by Adobe and Microsoft. A TrueType superset that can carry CFF (PostScript) outlines.

A document created by Apple's Pages word processor on macOS / iOS. Internally a ZIP bundle of XML and preview imagery.

A fixed-layout document format used anywhere the exact look of a page matters — contracts, invoices, manuals, and printable forms. PDFs render the same way across OSes and printers.

Server-side PHP source. Powers a huge slice of the web via WordPress, Laravel, and classic LAMP stacks.

The macOS Installer package. Used to ship apps that require system-level changes rather than a simple .app drag-to-Applications.

A lossless raster image format with transparency (alpha channel). The default for logos, screenshots, and UI assets on the web.

PowerPoint's pre-2007 binary format. Still shared in government and large enterprises; macro-enabled variants need the usual caution.

PowerPoint's format from 2007 onward. A ZIP bundle of XML and media that also opens cleanly in Keynote and LibreOffice Impress.

A PowerShell script. Used for Windows administration, server operations, and DevOps pipelines.

Adobe Photoshop's native format. Preserves layers, masks, smart objects, and adjustment layers for ongoing edits.

Python source code. Ubiquitous in data analysis, ML, automation, and backends — runs on every mainstream OS.

WinRAR's proprietary archive format. Higher compression ratios than ZIP and optional recovery records for repairing damaged splits.

A camera RAW file containing untouched sensor data. Each vendor ships its own flavour — Canon .cr3, Nikon .nef, Sony .arw, etc.

Source for Ruby, Yukihiro Matsumoto's dynamic scripting language. Rails brought it into the web-development mainstream.

Red Hat-family Linux package format (RHEL, CentOS, Fedora, openSUSE). Managed with dnf / yum / zypper.

Source for the Rust systems language — memory safety without a garbage collector, powering web backends, CLIs, and even kernels.

Microsoft's cross-platform formatted-text format. Richer than plain text, and the lowest common denominator for formatted documents on every OS.

A script executed by a Unix shell (bash, zsh, sh). A shebang on line one picks the interpreter; the execute bit controls whether it can run.

Aladdin Systems' (now Smith Micro) 1987 archive format for classic Mac. The de-facto standard for Mac software distribution before OS X, and still occasionally encountered when digging through legacy Mac media.

A text file of SQL statements — queries, DDL, DML — used for backups, migrations, and ad-hoc analysis.

A self-contained relational database in a single file. Embedded in iOS, Android, and browsers — the de-facto standard for mobile local storage.

An XML-based vector image format. Logos, icons, and charts stay crisp at any size and can be styled with CSS or manipulated with JavaScript.

Source for Apple's modern Swift language. First-choice for iOS, macOS, watchOS, and tvOS apps.

A Unix-born archive format. Plain tar is uncompressed and is commonly paired with gzip or xz to produce `.tar.gz` / `.tar.xz`.

The workhorse of print and scanning. Supports uncompressed, LZW, and JPEG-compressed payloads and can hold multiple pages per file.

A configuration-focused data format with unambiguous syntax. Adopted by Rust's Cargo and Python packaging (pyproject.toml).

Microsoft's typed superset of JavaScript. The de-facto standard for serious front-end and Node.js projects.

The TrueType font format originated at Apple and was standardised with Microsoft. Widely supported on Windows, macOS, and Linux.

The simplest possible text file, with no formatting. Works everywhere, and is the default for logs and quick notes.

A binary instruction format that runs near-native in browsers. Compiled from Rust / C / C++ for heavy computation or fast web apps.

The uncompressed audio container co-developed by Microsoft and IBM. A staple in music production and raw audio exchange.

The single-file web archive produced when Safari saves a page on macOS or iOS. Internally a binary plist bundling HTML, images, CSS, and JS.

A Google-led web video container built around VP8/VP9/AV1. Natively supported by HTML5 `<video>` in the major browsers.

A modern web image format developed by Google. Produces smaller files than JPEG or PNG at equivalent quality, supports both lossy and lossless modes, and carries an alpha channel.

Microsoft's proprietary audio codec. Paired with WMV, it was the default for Windows music services and voice recorders in the 2000s.

Microsoft's video container, widespread in the 2000s and still found in legacy enterprise systems and lecture recordings.

The first-generation web font format. A zlib-compressed TTF/OTF wrapper introduced around 2009. Largely superseded by WOFF2.

A web-optimised font format. Takes TTF/OTF and adds Brotli compression — about 30% smaller than WOFF1.

The pre-2007 binary Excel format. Still emitted by legacy enterprise systems and a classic malware delivery vector because of VBA macros.

Excel's default format since 2007. Under the hood, a ZIP bundle of XML and media — also readable by Numbers and LibreOffice Calc.

A tag-based markup for structured data. Still everywhere — configs, RSS feeds, SOAP APIs, and Office Open XML packages.

LZMA2-based high-ratio compression. Common in Linux kernel and distribution tarballs, steadily displacing gzip.

A human-friendly data format. Ubiquitous in CI/CD, Kubernetes, Docker Compose, and modern configuration files.

The most common archive format for bundling and compressing multiple files. Built into every major OS, widely used for email attachments and downloads.