Common file types

Extension	Type	Characteristics
.aam	media file	MacroMedia Shockwave
.arc	archive file (obsolete)	Open with PKZip or WinZip
.asp	web page	active server page – used to code Web pages that connect to databases
.au	audio	Sound file – open with player – used on older Web pages
.avi	video clip	Audio/Video Interleaved – movie clip – open with mplayer, IE, or Navigator with plugin
.bak	backup file	Used by many applications – often created automatically
.bat	application	DOS batch file – run by double-clicking in Win95 – edit with Notepad
.bmp	graphic file	Microsoft bitmap – open in MS Paint or graphics program
.cab	archive	Microsoft installation achive (cabinet file) – similar to .zip archive
.cfg	—	Configuration file
.cgi	—	Common Gateway Interface – used to exchange information with a server (often used with Perl)
.chk	—	Data recovered after running Checkdisk
.css	style sheet	plain text file containing web page style preferences
.csv	data	Comma Separated Value file – a way of presenting tabular data in a text file – usually viewed in MS Excel.
.dat	data file	Used by several applications. Not to be opened directly.
.dcr	media file	Macromedia Shockwave movie
.dir	media file	Macromedia Director file – provides animation and interactivity
.dll	dynamic link library	Software used by Windows to provide services to applications
.doc	document	Microsoft Word file
.dot	template	Microsoft Word template
.drv	device driver	Used to control hardware – (old)
.dtd	text	document type definition
.exe	application	self-extracting or executable file – run by double-clicking in Win95
.faq	data file	Frequently Asked Questions – almost always a text file
.fla	media	Macromedia Flash animation file – requires Shockwave
.fnt	—	Font file
.gif	image	graphic in GIF format – open in web browser or graphics program
.gz	application	compressed archive file created by Gzip in the UNIX operating system
.hqx	archive	Compressed Macintosh file archive created by Binhex
.htm	text file	hypertext document [same as .html] – open in a web browser – edit in any word-processor or text editor
.ico	Windows icon	Open with an icon editor
.ini	—	Initialisation file
.jar	Java	Java compressed archive file
.jav	Java	cross platform programming language used to create complex interactive forms and special effects
.jpg	image	Graphic in JPEG format (Joint Photographic Experts Group) View with web browser or image editing program
.js	JavaScript	part of Web page used to create interactive effects such as mouse roll-overs and pop-up boxes
.jso	—	Java server page
.kbd	data file	Keyboard layout data
.log	data file	Created by many applications – usually a text file – edit in any text editor
.mid	audio	audio file in MIDI format
.mov	video	QuickTime movie – view using IE or Netscape using plug-in
.mp3	audio	Audio file in MP3 format – CD-quality sound, with 10x compression
.mpg	movie	Video movie in MPEG format (Motion Picture Experts Group)
.old	—	Backup file (generic)
.pdf	application	Portable Document Format – requires Adobe Acrobat reader
.pl	application	Perl source file – text file, editable in any text editor
.png	image	graphic in Portable Network Graphics format – can work on all platforms
.ppt	application	Microsoft PowerPoint file – used for creating slides and overhead presentations
.pub	—	Microsoft Publisher page template file
.ram	audio	Real Audio file – open in browser with RealAudio plug-in
.rtf	application	Rich Text Format - word-processor file with formatting codes
.scr	screen saver
.sea	application	Self-extracting archive - Apple-Mac – requires Stuffit
.sig	signature	Appended to outgoing email messages – editable in text editor
.swf	media	Macromedia Shockwave Flash animation movie
.sys	—	DOS system file – device driver or hardware configuration info
.tar	application	file archive created in the Unix operating system
.tar.gz	application	.tar archive compressed by Gzip
.tif	image	Tagged Image File format – graphic file – editable in graphics program
.tmp	—	temporary file – used by many programs
.ttf	—	True Type Font file – view with fontview
.txt	text	contains only ASCII code – also called ‘text file’ – editable in any text editor
.wav	audio	Sound file in Waveform format
.wsz	graphics	Winamp skin – visual interface for audio control board
.xls	application	Microsoft Excel worksheet file
.xml	Web page	extensible markup language – a plain text file for web pages
.zip	application	compressed file – open with WinZip or PKZip

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