File Extensions

Overview

This article is a quick guide to file extensions. It covers what file extensions are, some important and common file extensions, and little definitions of them all.


File Extensions
File Extensions

What Are File Extensions?

File extensions are an indication of the format or type of a file. These are mentioned after the name of a file, separated with a dot '.', for example, "Filename.txt". File extensions are usually three or four characters long, and in rare cases, two characters long. These are used by the operating system to determine the program in which a file is to be opened when the user clicks on it. 

Some Common File Extensions

Document File Extensions

.txt 
Text File
Simple text file with no special formatting.
.doc
Microsoft Word File 
Microsoft  Word document.
.xls
Microsoft Excel File 
Microsoft Excel document, spreadsheet file.
.ppt
Microsoft PowerPoint File 
Microsoft PowerPoint document, presentation file.
.pub
Microsoft Publisher File 
Microsoft Publisher document, slightly different from word. In Publisher, the importance is given to page layout and design rather than text composition.
.wps
Microsoft Works File 
Microsoft Works document, Works being the outdated alternative of Microsoft Word.
.wpd
WordPerfect File 
WordPerfect document, WordPerfect being a word processor, which was extremely popular in the 80s.
.pdf
PDF File
PDF stands for Portable Document File, PDF was developed by Adobe in 1992 and its speciality is to present documents with consistency across various platforms.
.rtf
RTF File 
RTF stands for Rich Text Format, it is used to create formatted text files, unlike the basic text file.

Video File Extensions

.mov
MOV/Apple QuickTime Movie File 
MOV file is a common multimedia file format which was developed by Apple and is compatible with both Macintosh and Windows.
.mkv
MKV/Matroska Multimedia Container
MKV file is a video file stored in Matroska multimedia container format.
.mp4
MP4/MPEG-4 Video File 
MP4 stands for MPEG 4 Part 14, it is a file that is commonly used to store videos, however, it may also contain images or subtitles.
.m4v
M4V/Apple MP4 Video File
M4V is an MPEG 4 file that is used to store videos downloaded from Apple iTunes store.
.mpg or .mpeg
MPG/MPEG Video File
An MPG file is a video file that uses a digital video format set by MPEG(Moving Picture Experts Group).
.avi
AVI/Audio Video Interleave File 
An AVI file is a video file saved in the Audio Video Interleave multimedia container format. This format was created by Microsoft and stores audio and video data in a variety of codecs.
.flv
FLV/Flash Video File 
FLV is a file format developed by Adobe. An FLV file is a flash compatible video file, it can be exported by the Flash Video Exporter or any other program with FLV file support.
.rm
RM/RealMedia File 
An RM file is a multimedia file that is saved in the RealMedia multimedia container format, this format was developed by RealNetworks. An RM file can be used to store either audio in RealAudio format or video in RealVideo format, as well as both. These files are mainly used for streaming purposes. 
.wmv
WMV/Windows Media Video File 
A WMV file is a video file that is based on ASF(Advanced Systems Format), developed by Microsoft. 
.vob
DVD VOB/Video Object File 
A VOB file is a movie data file from a disc, it contains the majority of data on the disk, including video, audio, subtitles, DVD menus, etc.
.3gp
3GP Multimedia File
A 3GP file is a multimedia file stored in a video and audio container format, this format was developed by 3GPP(3rd Generation Partnership Project).

Audio File Extensions

.mp3
MP3 Audio File
MP3 stands for MPEG Audio Layer-3, it is a compressed audio file format developed by MPEG(Moving Picture Experts Group). The speciality of MP3 is that it keeps the sound quality of an original recording but is significantly smaller.
.m4a
M4A/MPEG 4 Audio File 
M4A is MPEG 4 audio file, it is a format that stores both compressed audio and video data.
.mpa
MPA/MPEG 2 Audio File 
MPA is MPEG 2 audio file, this means that it is compressed with MPEG layer 2 compressions. It reduces the file size while slightly affecting the overall sound quality.
.aif
Audio Interchange Audio FIle
An AIF(Audio Interchange File) is created using AIFF(Audio Interchange File Format) and contains uncompressed CD quality audio.
.cda
CDA/CD Audio Track Shortcut File
CDA file is a shortcut to a track on an audio CD, it plays the referenced track on the CD when opened. Therefore it only works correctly when the CD is inside the CD drive.
.wma
WMA/Windows Media Audio File 
A WMA(Windows Media Audio) file is a file that is saved in ASF(Advanced Systems Format), which is a proprietary format developed by Microsoft. 
.wpl
WPL/Windows Media Player Playlist
A WPL(Windows Media Player Playlist) file is simply a playlist of songs or videos that can be played in Windows Media Player.
.ram
RAM/Real Audio Metadata File 
A RAM(Real Audio Metadata) file is a link file used by RealPlayer, which is a program used for streaming audio and video on the internet.
.mid or .midi
MIDI Audio File 
MIDI stands for Musical Instrument Digital Interface, it is used by music authoring and mixing programs, and MIDI hardware devices.
.wav
WAV/WAVE Audio File
A WAV file is simply a file saved in WAVE format. WAVE format is a standard digital audio file format that stores waveform data.

Executable File Extensions

.exe
Windows EXE/Executable File
An EXE file contains an executable program for Windows, it is the standard file extension used by Windows programs.
.com
COM/MS DOS Command File 
A COM file is similar to an EXE file, it contains an executable program that can be run by MS DOS and Windows. It differs from an EXE file in terms of size, it has a maximum size of 64KB, and has no header or metadata.
.jar
JAR/Java Archive File 
JAR files are used by JRE(Java Runtime Environment), which is a platform for executing Java programs.
.py
PY/Python File 
A PY file is a program file or script written in Python, it can be created or edited with a text editor, but requires a Python interpreter to run.
.bat
DOS BAT/Batch File 
A BAT file is a DOS batch file used to execute commands with Command Prompt.
.bin
BIN/Binary File 
A BIN file stores data in binary format.
.wsf
WSF/Windows Script File 
A WSF file is an executable script for Windows, it can include JScript and VBScript, and may also include XML features.
.apk
APK/Android Package File
An APK file is an app developed for the Android OS.

Graphics File Extensions

.jpg or .jpeg
JPEG Image
A JPG file is an image saved in a compressed image format normalized by JPEG(Joint Photographic Experts Group). It is commonly used by digital cameras to store photos.
.gif
GIF/Graphical Interchange Format Image 
A GIF file is an image file saved in Graphical Interchange Format and it maintains the quality of an image while compressing it.
.png
PNG/Portable Network Graphic Image 
A PNG file is an image file saved in Portable Network Graphic format, it provides lossless compression, similar to a GIF file. PNG files are most commonly used to store web graphics and images with a transparent background. 
.psd
Adobe PSD/Photoshop Document Image
A PSD file is an image file created by Adobe Photoshop, which is a photo editing software. These files may include some Photoshop specific elements such as image layers, layer mask, annotations, etc.
.ai
Adobe Illustrator File 
An AI file is a drawing file created with Adobe Illustrator, which is a vector graphics editing software. These files are normally used for logos and print media. 
.bmp
BMP/Bitmap Image File
A BMP file is an uncompressed raster image that consists of a rectangular grid of pixels.
.ico
Icon File 
An ICO file contains an icon, which can be used for a windows program, a file or a folder.
.max
MAX/3ds Max Scene File 
A MAX file is a 3D file created by 3ds Max. 3ds Max is a 3D modeling, animation and rendering software.
.obj
OBJ/Wavefront Object File 
An OBJ file is a standard 3D image format file that can be run by several 3D image editing programs.
.ps
PS/PostScript File 
A PS file is an image saved in PostScript page description language and it can contain vector graphics, raster graphics, and text.
.tif or .tiff
TIFF image 
TIF stands for Tagged Image File, it is an image saved in TIFF(Tagged Image File Format), which is a high quality graphics format.

System File Extensions

.sys
SYS/Windows System File
A SYS file is a system file used by DOS and Windows OS, SYS files contain functions, system settings and variables. 
.tmp
TMP/Temporary File 
A TMP file is a temporary file that is created automatically by a program, this file is used as a backup or a cache file.
.msi
MSI/Windows Installer Package 
An MSI file is a package file that contains installation related information for an installer to access.
.bak
BAK/Backup File 
A BAK file is a backup file of Google Chrome or Mozilla Firefox bookmarks file. This file can be used in case the original bookmarks file is lost or corrupt.
.cab
CAB/Windows Cabinet File 
A CAB file is a Windows Cabinet file stored in an archive format, it contains compressed data, which is used for installations.
.cpl
CPL/Windows Control Panel File 
A CPL file is an module in the Windows Control panel, such as Displays, Mouse, Sound, etc.
.dll
DLL/Dynamic Link Library File 
A DLL file is a library that contains a set of procedures and/or drivers that are used by a Windows program.
.dmp
DMP/Windows Dump File 
A DMP file contains data that is dumped from a program’s memory. It is created when a program has an error or crashes.
.drv
DRV/Device Driver File 
A DRV file is a driver file that contains commands and procedures for a hardware device to communicate with the operating system.
.cur
CUR/Windows Cursor File 
A CUR file contains a cursor image or animation for the mouse pointer.
.icns
ICNS/macOS X Icon Resource File 
An ICNS file is an icon file that is used by macOS.
.ini
INI/Initialization File 
An INI file is a file that contains configuration for a Windows program to initialize the program settings.
.lnk
LNK/Windows Shortcut File
An LNK file is simply a shortcut used by Windows, for an original file.

Web File Extensions 

.htm and .html
HTM/HTML File 
HTML stands for Hypertext Markup Language, an HTM or HTML file is a webpage used by web browsers.
..xhtml
XHTML File 
An XHTML file is a web page written in XHTML(Extensible Hypertext Markup Language), which is an xml centric version of HTML. 
.js
JS/JavaScript File 
A JS file is a text file that contains a JavaScript code, which is used to run JavaScript instructions in web pages.
.php
PHP Source Code File 
A PHP file is a web page that contains PHP code, PHP is a Hypertext Processor, which can include PHP functions to process online forms and access data from a database.
.cer
CER/Internet Security Certificate 
A CER file is a file that verifies the authenticity of a website and is provided by a Certificate Authority, such as VeriSign.
.asp and .aspx
ASP File 
ASP stands for Active Server Page, an ASP file is a web page that stays on a web server and is parsed and then sent to the client's browser. An ASP file can contain scripts written in VBScript and JavaScript.
.css
CSS/Cascading Style Sheet File 
A CSS or cascading style sheet file is a file that is used to format the contents of a web page.
.jsp
JSP/Java Server Page File 
A JSP file is a server generated web page, similar to an ASP or a PHP file, but it contains Java code.
.rss
RSS/Rich Site Summary File 
An RSS or Rich Site Summary file is a file saved in an XML based syndication format, it contains web content and metadata, such as author’s name and publishing date. It is a text only format and is commonly used by websites for distributing information. 
.part
PART/Partially Downloadable File 
A PART file is a file that is partially downloaded from the internet and is used for downloads that are in progress or stopped. Some of these files can later be resumed with the same program that first downloaded them.
.cfm
CFM File 
A CFM file is a web page that contains ColdFusion or CFML(ColdFusion Markup Language) code, it is actively run by a ColdFusion web server.
.cgi
CGI/Common Gateway Interface
A CGI file is a Common Gateway Interface script that is executed by a web server to create active pages. It is written in Perl or C, which are both programming languages.

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