Common Windows file extensions

Windows file names have two parts, the name, then a period and the extension (suffix). The extension is a three- or four-letter abbreviation that comes after the period. For example, in letter.doc the filename is letter and the extension is doc.

Extensions are important because they tell your computer what icon to use for the file, and what application can open the file. For example, the doc extension tells your computer that the file is a Microsoft Word file.

If you want to open a MAC OS X file in Windows, you may need to add the extension to a MAC OS X file name so Windows can recognize it. For example, if you have a Word 6 MAC OS X document named letter that you want to open in Windows, you need to rename the file letter.doc so that Word in Windows will recognize and open the file.

The list below explains some of the common extensions.

Note: This list is by no means a complete and exhaustive list of file extensions. If the file extension you are using is not listed below, you may find the information by looking in the software manual or software application's Web site.

Note: If none of your file names have extensions, file extensions are hidden. See

File Extension File Type
.AIFF or .AIF Audio Interchange File Format
.AU Basic Audio
.AVI Multimedia Audio/Video
.BAT PC batch file
.BMP Windows BitMap
.CLASS or .JAVA Java files
.CSK ClarisWorks for Windows
.CVS Canvas
.DBF dbase II, III, IV data
.DIF Data Interchange format
.DOC Microsoft Word for Windows/Word97
.EPS Encapsulated PostScript
.EXE PC Application
.FM3 Filemaker Pro databases (the numbers following represent the version #)
.GIF Graphics Interchange Format
.HQX Macintosh BinHex
.HTM or .HTML Web page source text
.JPG or JPEG JPEG graphic
.MAC MacPaint
.MAP Web page imagemap
.MDB MS Access database
.MID or .MIDI MIDI sound
.MOV or .QT QuickTime Audio/Video
.MTB or .MTW MiniTab
.PDF Acrobat -Portable document format
PageMaker (the numbers following represent the version #) P=publication, T=template
.PNG Public Network graphic
.PPT PowerPoint
.PSD Adobe PhotoShop
.PSP PaintShop Pro
.QXD QuarkXPress
.RA RealAudio
.RTF Rich Text Format
.SIT Stuffit Compressed Archive
.TAR UNIX TAR Compressed Archive
.TIF TIFF graphic
.TXT ASCII text (Mac text does not contain line feeds--use DOS Washer Utility to fix)
.WAV Windows sound
.WK3 Lotus 1-2-3 (the numbers following represent the version #)
.WKS MS Works
WPD or .WP5 WordPerfect (the numbers following represent the version #)
.XLS Excel spreadsheet
.ZIP PC Zip Compressed Archive

Showing File Extensions

If none of your file names have extensions, file extensions are hidden. To show file extensions:

  1. Click on the start menu, and type "Show hidden files and folders," then press the enter key. 

  2. Click on the "View" tab, and make sure Hide extensions for known file types is not checked.

  3. Click "Apply" then "OK".
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