Complete Guide to File Extensions: What They Are and How to Open Them

In the vast digital world, file extensions (those letters after the dot, like .jpg or .pdf) are fundamental: they tell the operating system what kind of data the file contains and which program to use to open it.

This guide analyzes the most common extensions by category, suggesting the best software to view or edit them on Desktop (Windows/macOS) and Mobile (Android/iOS).

📄 Documents and Text

These files contain formatted text, images, and other layout elements. They are the standard formats for work and study.

.PDF (Portable Document Format)

Created by Adobe, this is the global standard for documents that need to look identical on any device.

Desktop: Adobe Acrobat Reader, Google Chrome/Edge (viewing), Foxit Reader.

Mobile: Adobe Acrobat Reader, Google PDF Viewer, Files (iOS).

.DOCX / .DOC (Microsoft Word)

The standard format for word processing. .docx is the modern XML-based version (lighter and safer), while .doc is the legacy version.

Desktop: Microsoft Word, LibreOffice Writer, Google Docs (via browser).

Mobile: Microsoft Word, Google Docs, WPS Office.

.XLSX / .XLS (Microsoft Excel)

Spreadsheets used for data analysis, tables, and charts.

Desktop: Microsoft Excel, LibreOffice Calc.

Mobile: Microsoft Excel, Google Sheets.

.TXT (Plain Text)

Pure text without formatting (no bold, colors, or images). Universal.

Desktop: Notepad (Windows), TextEdit (macOS), Notepad++.

Mobile: Any text editor, Moon+ Reader.

🖼️ Images and Graphics

Visual files used for photography, web graphics, and design.

.JPG / .JPEG (Joint Photographic Experts Group)

The most common format for photographs. It uses "lossy" compression to reduce file size while maintaining good visual quality.

Desktop: Photos (Windows/macOS), IrfanView, Photoshop.

Mobile: Google Photos, Gallery (iOS/Android).

.PNG (Portable Network Graphics)

Supports transparency and uses "lossless" compression. Ideal for logos and web graphics.

Desktop: Any image viewer.

Mobile: Google Photos, System Gallery.

.GIF (Graphics Interchange Format)

Supports simple animations and limited transparency. Widely used on social media.

Desktop: Web Browser, standard image viewers.

Mobile: WhatsApp, Telegram, GIPHY App.

.SVG (Scalable Vector Graphics)

Vector images based on XML code. They can be scaled infinitely without losing quality.

Desktop: Web Browser (Chrome, Edge), Adobe Illustrator, Inkscape.

Mobile: SVG Viewer, Web Browser.

.HEIC (High Efficiency Image Container)

The modern standard format for photos taken on iPhones. High quality in half the space compared to JPG.

Desktop: Photos (macOS), HEIF Extensions for Windows.

Mobile: Photos (iOS), Google Photos (Android).

🎵 Audio and Music

Formats for songs, voice recordings, and sounds.

.MP3 (MPEG Audio Layer III)

The most famous audio format in the world. Compressed, compatible with almost everything.

Desktop: Windows Media Player, iTunes/Music, VLC Media Player.

Mobile: Any music player (Spotify for local files, Samsung Music).

.WAV (Waveform Audio File)

High-quality uncompressed audio. Very heavy, used by professionals.

Desktop: VLC, Audacity (editing).

Mobile: VLC for Mobile.

.FLAC (Free Lossless Audio Codec)

Compressed audio but without loss of quality (lossless). Loved by audiophiles.

Desktop: VLC, Foobar2000.

Mobile: VLC, PowerAmp (Android).

🎬 Video

Formats for movies, clips, and recordings.

.MP4 (MPEG-4 Part 14)

The universal standard for video. Balances quality and file size perfectly. Supported by all modern devices.

Desktop: Windows Media Player, QuickTime, VLC.

Mobile: Native player, VLC, MX Player.

.MOV (QuickTime Movie)

Developed by Apple. High quality, often used by iPhones and Macs.

Desktop: QuickTime Player (macOS), VLC (Windows).

Mobile: Photos (iOS), VLC (Android).

.MKV (Matroska Video)

A flexible container that can hold unlimited video, audio, and subtitle tracks in one file. Popular for high-quality movies.

Desktop: VLC Media Player (Highly Recommended).

Mobile: VLC, MX Player.

.AVI (Audio Video Interleave)

An older Microsoft format. Still common, but less efficient than MP4.

Desktop: Windows Media Player, VLC.

Mobile: VLC.

📦 Archives and Compressed Files

Folders compressed into a single file to save space or group items for sharing.

.ZIP

The universal compression standard. Built into almost all operating systems.

Desktop: Windows Explorer, macOS Archive Utility, 7-Zip.

Mobile: Files (iOS/Android), ZArchiver.

.RAR

A proprietary format that offers better compression than ZIP but requires specific software to open.

Desktop: WinRAR, 7-Zip.

Mobile: RAR app, ZArchiver.

.7Z (7-Zip)

Open-source format with a very high compression ratio.

Desktop: 7-Zip (Windows), Keka (macOS).

Mobile: ZArchiver.

⚙️ Executables, Installers & System Files

Files used to install software or run programs. Warning: Only download and open these files from trusted sources.

.APK (Android Package Kit)

The installer format for Android apps. Used to install apps manually (sideloading) outside the Google Play Store.

Desktop: Requires an emulator like BlueStacks or Nox Player.

Mobile: Android Package Installer (Native). Not supported on iOS.

.EXE (Executable File)

The standard program file for Windows. Double-clicking usually installs or runs an application.

Desktop: Windows (Native). Not compatible with macOS (without software like Wine/Crossover).

Mobile: Not supported (requires complex emulation).

.DMG (Apple Disk Image)

A "virtual disk" widely used to distribute software on macOS. You open it, and it mounts like a drive.

Desktop: macOS (Native). Windows can only extract it (using 7-Zip) but not run it.

Mobile: Not supported.

.ISO (Optical Disc Image)

A digital copy of a CD, DVD, or Blu-ray. Often used for operating system installers (like Linux or Windows).

Desktop: Windows/macOS (can "mount" natively), VLC (for video ISOs).

Mobile: VLC (for video), ZArchiver (to extract contents).