FILES & SOFTWARE
A file extension is the suffix commonly used to identify a file's format or the software associated with opening it. Extensions are useful clues, but they do not independently guarantee that a file is valid, safe, or actually contains the format suggested by its name.
Some extensions identify containers that can hold different streams or types of data, while others represent more specific formats.
Documents & Text
| Extension | Format | Typical Use |
|---|---|---|
.txt | Plain text | Unformatted text |
.md | Markdown | Structured plain-text documentation |
.csv | Comma-separated values | Tabular data exchange |
.pdf | Portable Document Format | Documents designed for consistent presentation |
.docx | Word Open XML | Editable word-processing documents |
.xlsx | Excel Open XML | Spreadsheets and structured data |
.pptx | PowerPoint Open XML | Presentations |
.rtf | Rich Text Format | Formatted text interchange |
Images
| Extension | Format | Typical Characteristics |
|---|---|---|
.jpg / .jpeg | JPEG | Lossy compression commonly used for photographs. |
.png | PNG | Lossless compression with transparency support. |
.gif | GIF | Limited-color images and simple animation. |
.webp | WebP | Supports lossy and lossless image compression. |
.avif | AVIF | Modern image format based on AV1 image coding technology. |
.svg | SVG | XML-based vector graphics. |
.tif / .tiff | TIFF | Flexible format used in imaging, scanning, and publishing workflows. |
Audio & Video
| Extension | Format | Typical Use |
|---|---|---|
.mp3 | MP3 | Compressed digital audio |
.wav | WAV | Uncompressed or PCM-based audio |
.flac | FLAC | Lossless audio compression |
.aac | AAC | Compressed digital audio |
.mp4 | MPEG-4 container | Common container for video, audio, subtitles, and metadata |
.webm | WebM | Multimedia container commonly used for web media |
.mkv | Matroska | Flexible multimedia container |
.mov | QuickTime container | Multimedia container used in many video workflows |
Archives & Compressed Files
| Extension | Format | Typical Use |
|---|---|---|
.zip | ZIP | General-purpose file archiving and compression |
.7z | 7z | Compressed archive format |
.rar | RAR | Compressed archive format |
.tar | TAR | File archive commonly used on Unix-like systems |
.gz | Gzip | Compression format frequently used with Unix tools |
.tar.gz | TAR + Gzip | Archived and compressed Unix-style package |
An Extension Does Not Prove File Safety
A familiar extension does not prove that a downloaded or received file is trustworthy. Unexpected files should be handled carefully, particularly when they originate from unknown sources.