List of file extensions

This is a list of common file extensions. Keep in mind that extensions are arbitrary and, whenever there's any doubt, the file command will generally provide a more accurate indicator of file contents than the extension.

0-9

• .1, etc. - man pages generally fall into numerical categories (though there are others) and have a suffix indicating the section. Logrotate also names old log file with an extra numerical extension.

A

• .asm - assembly language source code
• .au - Sun audio file

B

• .blend - Blender 3D scene
• .bmp - Bitmap image format
• .bz2 - a file processed with bzip2 compression (see .tar)

C

• .c - C source code
• .class - Java class, compiled bytecode
• .conf - configuration file
• .cfg - configuration file
• .cpp - C++ source code
• .cc - C++ source code (not as common as *.cpp)
• .css - CSS, Cascading StyleSheet
• .csv - a plain text file containing comma separated values

D

• .db - Berkeley DB
• .deb - Debian package
• .desktop - Desktop entry, standard link/shortcut/launcher format
• .diff - patch/difference file generated by diff
• .dtd - DTD, Document Type Definition for XML data

G

• .gif - image file which uses the patented LZW compression algorithm
• .gz - a file processed with gzip compression (see .tar)

H

• .h - header file
• .html/*.htm - HTML

J

• .jar - Java Archive zip compressed file containing Java classes/sources
• .java - Java source file

K

• .kwd - KDEs native format for their Kword word processor
• .ksp - KDEs native format for their Kspread spreadsheet application
• .kss - KDEs screensaver format

L

• .log - logging data from some application, usually in plain text format

M

• .m3u - playlist file, originates from WinAmp
• .m4a - compressed MPEG-4 audio file without DRM
• .m4p - compressed MPEG-4 audio file with DRM
• .md5 - file containing an md5sum for a single file. IE: foobar.iso.md5 contains the md5sum for foobar.iso
• .md5sums - file containing a list of MD5 checksums, generated and used by md5sum
• .mo - Compiled message catalog, generated and used by GNU gettext
• .mpg or .mpeg - compressed video file
• .mp3 - compressed MP3 audio file

O

• .o - object file. Source code that has been compiled but not linked
• .ogg - Ogg Vorbis sound file

P

• .patch - patch file, generated by diff, to be used with patch
• .pdf - PDF, Adobe Portable Document file.
• .php - PHP source file
• .phps - PHP source file in which the source is intended to be displayed rather than executed
• .phtml - PHP source file (uncommon)
• .pl - Perl source code
• .pls - a playlist file (file of filenames or URLs)
• .png - PNG image file
• .pov - source code for the povray ray tracer
• .properties - value containing configuration values, used by Java applications
• .ps - postscript file. Like pdf, but without form functionality.
• .py - python script
• .pyo - python optimized bytecode
• .pyc - python compiled bytecode

R

• rc - not really an extension, but often found at the end of 'run control' (or 'resource configuration') files such as 'bashrc'.
• .rdf - "Resource Description Framework" file, XML based format
• .rpm - originally a Red Hat package (the RedHat Package Manager) but now many distros are rpm based.
• .rtf - rich text format. A Lowest common denominator format for exchanging documents between different word processors

S

• .s or .S - assembly language source code
• .sh - shell script (as with nearly all extensions, this is optional)
• .so - Shared object/library file

T

• .tar - a file archived with tar (the tape archiver) - often also compressed with gzip, bzip2, etc., in which case it will have a double extension of 'tar.gz', '.tar.bz2', etc.
• .tgz - possibly a .tar.gz file with the shorter extension but more likely these days to be a Slackware package like a .deb or .rpm
• .tga - Targa image file
• .ttf - TTF (True Type) font
• .txt - plain text file.

W

• .wav - uncompressed audio format

X

• .xbel - XML based bookmarks file
• .xsd - XML Schema
• .xml - XML file
• .xsl - XSL stylesheet
• .xpm - X pixmap

Z

• .Z - rarely seen anymore, a compressed file, often tarred as .tar.Z
• .zip - Compressed Archive. More common on Windows, but can be read/written on UNIX using zip and unzip commands