What Are File Extensions? A Complete Guide

File Extensions

File extensions are suffixes that come after a file name and reveal the kind of data or format that the file contains. The operating system uses these extensions to help decide which application should open the file. After the dot, file extensions usually include three or four characters (e.g., .txt, .jpg).

Text Files

• .txt—Plain text file (contains unformatted text).
• .rtf—Rich Text Format (supports basic text formatting).
• .doc—Microsoft Word document (used in older versions of Word).
• .docx—Microsoft Word document (from Word 2007 onwards).
• .odt—OpenDocument Text (open standard for word processing documents).
• .md – Markdown file (text-based format used for documentation).

Image Files

• .jpg / .jpeg – JPEG image (commonly used for photographs).
• .png – Portable Network Graphics (supports transparency).
• .gif – Graphics Interchange Format (supports simple animations).
• .bmp—Bitmap image (uncompressed raster format).
• .tiff / .tif – Tagged Image File Format (used for high-quality images).
• .svg – Scalable Vector Graphics (used for vector-based images).
• .webp—WebP image (used for high-quality web images with smaller file sizes).

Audio Files

• .mp3 – MPEG Audio Layer 3 (common audio format for music).
• .wav – Waveform Audio File Format (uncompressed audio format).
• .flac – Free Lossless Audio Codec (lossless audio compression).
• .aac—Advanced Audio Coding (used for high-quality compressed audio).
• .ogg – Ogg Vorbis audio file (open-source compressed audio format).
• .m4a—MPEG-4 Audio (commonly used by Apple devices).
• .wma—Windows Media Audio (proprietary audio format from Microsoft).

Applications of Computer

Video Files

• .mp4—MPEG-4 video (widely used for video streaming and storage).
• .avi—Audio Video Interleave (older format, supports high-quality videos).
• .mkv—Matroska Video (open-source format that supports multiple audio, video, and subtitle tracks).
• .mov—QuickTime movie (used by Apple’s video player software).

Compressed/Archive Files

• .zip—ZIP compressed archive file (common compression format).
• .rar—RAR compressed archive file (requires special software like WinRAR to open).
• .tar—Tape Archive (used in Unix/Linux systems to bundle files together).
• .gz – Gzip compressed file (commonly used in combination with .tar for compression).
• .7z – 7-Zip compressed file (high compression ratio, requires 7-Zip software to open).
• .iso—ISO image (disk image format, typically used for optical discs like CDs/DVDs).

Executable File Extensions

• .exe: Executable file (Windows)
• .app: Application file (MacOS)
• .bat: Batch file (Windows)
• .sh: Shell script (Unix/Linux)
• .jar: Java Archive file (Java applications)
• .msi: Microsoft Installer file

Web Development/Code File Extensions

• .html: HTML file (web page)
• .css: Cascading Style Sheets file
• .js: JavaScript file
• .php: PHP script file
• .py: Python script file
• .java: Java source code
• .cpp: C++ source code
• .json: JavaScript Object Notation file (data format)
• .xml: Extensible Markup Language file
• .yaml: YAML file (configuration data)

System File Extensions

• .dll: Dynamic Link Library (Windows)
• .bak: Backup file
• .iso: Disk image file (used for creating/burning CDs/DVDs)
• .tmp: Temporary file
• .swp: Swap file (used by editors like Vim)

Database and Data File Extensions

• .db: Database file
• .sql: SQL database file (contains database queries)
• .mdb: Microsoft Access Database file
• .sqlite: SQLite database
• .csv: Comma-separated values (spreadsheet file)

Font File Extensions

• .ttf: TrueType font
• .otf: OpenType font
• .woff: Web Open Font Format

Backup File Extensions

• .bak: Backup file
• .dmg: Disk image (MacOS)
• .swp: Swap file (created when editing in Vim)

Miscellaneous File Extensions

• .torrent: BitTorrent file (used for file sharing)
• .log: Log file (record of system activities)
• .xsd: XML Schema Definition file
• .eml: Email message file (saved email)

Virtual Machine and Disk Image File Extensions

• .vmdk: VMware disk file
• .vdi: VirtualBox disk image
• .iso: Disk image used for virtual machines or ISO images for CDs/DVDs