Common File Extensions

ACE - ACE Archiver compression file.
AIF - Audio Interchange File used with SGI and Macintosh applications.
ANI - Animated cursors used in Microsoft Windows.
API - Application Program Interface.
ART - Clipart.
ASC - ASCII text file.
ASM - Assembler code.
ASP - Microsoft Active Server Page.
AVI - Audio/Video Interleaved used for Windows based movies.
BAK - Backup Files. 
BAS - BASIC programming language sourcecode.
BAT - MS-DOS batch file.
BFC - Briefcase document used in Windows.
BIN - Binary File.
BIN - MacBinary-encoded files.
BMP - Bitmap format.
BUD - Backup Disk for Quicken by Intuit.
BZ2 - Bzip2-compressed files.
C - C source file.
CAT - Security Catalog file.
CBL - Cobol code.
CBT - Computer Based Training.
CDA - Compact Disc Audio Track.
CDT - Corel Draw Template file.
CFML - ColdFusion Markup Language.
CGI - Common Gateway Interface. Web based programs and scripts.
CHM - Compiled HTML Help files used by Windows.
CLASS - Javascript Class file.
CLP - Windows Clipboard file.
CMD - Dos Command File.
COM - Command File.
CPL - Control panel item - The settings in Control Panels represent 
CPL files in the Windows\System folder.
CPP - C++ programming language source code.
CSS - Cascading Style Sheet. Creates a common style reference for a set of web pages.
CSV - Comma Separated Values format.
CMF - Corel Metafile.
CUR - Cursor in Microsoft Windows.
DAO - Registry Backup file for Windows registry.
DAT - Data file.
DD - Compressed Archive by Macintosh DiskDoubler.
DEB - Debian packages.
DEV - Device Driver. 
DIC - Dictionary file.
DIR - Macromedia Director file.
DLL - Dynamic Linked Library. Microsoft application file.
DOC - Document format for Word Perfect and Microsoft Word.
DOT - Microsoft Word Template.
DRV - Device Driver.
DS - TWAIN Data source file.
DUN - Dial-up networking configuration file.
DWG - Autocad drawing.
DXF - Autocad drawing exchange format file.
EMF - Enhanced Windows Metafile.
EML - Microsoft Outlook e-mail file.
EPS - Encapsulated PostScript supported by most graphics programs.
EPS2 - Adobe PostScript Level II Encapsulated Postscript.
EXE - DOS based executable file which is also known as a program.
FFL - Microsoft Fast Find file.
FFO - Microsoft Fast Find file.
FLA - Macromedia Flash movie format.
FNT - Font file. 
GIF - Graphics Interchange Format that supports animation. Created by CompuServe and used primarily for web use.
GID - Windows global index. Contains the index information used by "Help" in Windows.
GRP - Microsoft Program Manager Group.
GZ - Unix compressed file. 
HEX - Macintosh binary hex(binhex) file.
HLP - Standard help file.
HT - HyperTerminal files. 
HQX - Macintosh binary hex(binhex) file.
HTM - Hyper Text Markup. This markup language is used for web design. 
HTML - Hyper Text Markup Language. This markup language is used for web design.
ICL - Icon Library File.
ICM - Image Color Matching profile.
ICO - Microsoft icon image.
INF - Information file used in Windows.
INI - Initialization file used in Windows.
JAR - Java Archive. A compressed java file format.
JPEG - Compression scheme supported by most graphics programs and used predominantly for web use.
JPG - More common extension for JPEG described above.
JS - JavaScript File - A text file containing JavaScript programming code.
LAB - Microsoft Excel mailing labels.
LGO - Windows 9x startup logo.
LIT - eBooks in Microsoft Reader format.
LNK - Windows 9x shortcut file.
LOG - Application log file.
LSP - Autocad(visual) lisp program.
MAQ - Microsoft Access Query.
MAR - Microsoft Access Report.
MDB - Microsoft Access DataBase File.
MDL - Rose model file. Opens with Visual Modeler or Rational Rose.
MID - MIDI music file.
MOD - Microsoft Windows 9.x kernel module.
MOV - Quicktime movie.
MP3 - MPEG Audio Layer 3.
MPEG - Animation file format.
MPP - Microsoft Project File.
MSG - Microsoft Outlook message file.
MSG - Fidonet messages.
NCF - Netware command File.
NLM - Netware loadable Module.
O - Object file, used by linkers.
OCX - ActiveX Control: A component of the Windows environment.
OGG - Ogg Vorbis digitally encoded music file.
OST - Microsoft Exchange/Outlook offline file.
PAK - WAD file that contains information about levels, settings, maps, etc for Quake and Doom.
PCL - Printer Control Language file. PCL is a Page Description Language developed by HP.
PCT - Macintosh drawing format. 
PDF - Portable Document File by Adobe. Viewable in a web browser or 
with Adobe Acrobat.
PDF - Printer Description File. Provides printer support for certain
applications.
PDR - Port driver for windows 95. It is actually a virtual device driver (vxd).
PHP - Web page that contains a PHP script.
PHTML - Web page that contains a PHP script. 
PIF - Program Information File
PIF - Vector graphics GDF file(IBM Mainframe)
PIF - Macintosh Compressed archive
PL - Perl source code file.
PM - Perl Module. 
PM3 - PageMaker 3.0 document.
PM4 - PageMaker 4.0 document.
PM5 - PageMaker 5.0 document. 
PM6 - PageMaker 6.0 document. 
PNG - Portable Network Graphic file.
POL - System Policy file for Windows NT.
POT - Microsoft PowerPoint design template.
PPD - PostScript Printer description file used in Macintosh and Windows operating systems to provide printer specific features to a driver.
PPS - Microsoft PowerPoint slide show.
PPT - Microsoft PowerPoint presentation(default extension).
PRN - A print file created as the result of "printing to file".
PS - PostScript file. 
PSD - Native Adobe Photoshop format.
PSP - Paint Shop Pro image.
PST - Personal Folder File for Microsoft Outlook.
PUB - Microsoft Publisher document.
s PWL - Windows Password list file.
QIF - Quicken Import file.
RAM - RealAudio Metafile.
RAR - RAR compressed archive created by Eugene Roshall.
RAW - Raw File Format.
RDO - Raster Document Object. Proprietary file type used on Xerox 
Digipath Scan and Makeready workstations.
REG - Registry file that contains registry settings.
RM - RealAudio video file.
RPM - RedHat Package Manager.
RSC - Standard resource file.
RTF - Rich Text Format.
SCR - Screen Saver file.
SEA - Self-extracting archive for Macintosh Stuffit files.
SGML - Standard Generalized Markup Language.
SH - Unix shell script.
SHTML - HTML file that supports Server Side Includes(SSI).
SIT - Compressed Macintosh Stuffit files.
SMD - SEGA mega drive ROM file.
SVG - Adobe scalable vector graphics file.
SWF - Shockwave Flash file by Macromedia.
SWP - DOS swap file.
SYS - Windows system file used for hardware configuration or drivers.
TAR - Unix Tape Archive.
TGA - Targa bitmap.
TIFF - Tagged Image File Format. Universal graphics format supported 
by most graphics applications.
TMP - Windows temporary file.
TTF - True Type font. 
TXT - Text Format.
UDF - Uniqueness Definition File. Used for Windows unattended installations.
UUE - UU-encoded file.
VBX - Microsoft Visual basic extension.
VM - Virtual Memory file.
VXD - Windows 9x virtual device driver.
WAV - Waveform sound file.
WMF - Windows Metafile (graphics format).
WRI - Write Document: This is equivalent to RTF, Rich Text Format, 
that enables saving text with formatting information.
WSZ - Winamp Skin.
XCF - The GIMP's native image format.
XIF - Wang imaging file. Wang Image Viewer comes with Windows 95/2000.
XIF - Xerox Image file (same as TIFF).
XIF - Image file eXtended by ScanSoft is similar to TIFF and is a Pagis application format.
XLS - Microsoft Excel Spreadsheet.
XLT - Microsoft Excel Template.
XML - Extensible markup language.
XSL - XML style sheet.
ZIP - Compressed Zip archive.