(Approx. 591 words)

File Extensions
By Fran Damratowski, Refurbishing SIG Chair, Chesapeake PC Users Group, MD
www.chesapeakepcusersgroup.org
Refurbishing(at)chesapeakepcusersgroup.org

Obtained from APCUG with the author's permission for publication by APCUG member groups.

Have you ever wondered what the three alphanumeric extension at the end of a file name mean? (MS-DOS required filename to limited to eight characters for the base or root name and three characters for the extension. Windows 95 and above no longer have that limitation.) The three letters or numbers are a way for the computer user, software, and operating system to differentiate between and identify the program used to create a file (document, spreadsheet, database, etc.). We are all familiar with .exe for an executable file, .txt for a text document, and .pdf  for a PDF file. There are many other file extensions. The same file extension may be used for more than one program. There is no standard or organization for creating file extensions. This month we will begin to list some of the extensions.

Here is the A list of some of the extensions and the file types they represent. 

.a: An ADA program, Unix archive file, Macintosh assembly source code, Free Pascal Archive file for Linux or DOS
.a2b: A2B Player Playlist
.abx: Word Perfect Address Book file
.aby: AOL file
.adr: Address Book, Address Plus Database, After Dark Random Screen Saver Module, Opera , Smart Address adressbook, Web Browser Bookmark File
.albm: webAlbum Photo Album, Photosmart Photo Printing Album
.alz: ALZIip compressed file, game file
.aps: MS Visual C++ file, Flash (Italian), ArcPar Ver. 5 Symbology, Advanced Patching Systems with Error Checking
.arl: AOL Organizer file
.arj: Compression archive
.ars: Adobe After Effects Render, Artifax Report Editor
.asl: Adobe Photoshop Layer file, Quest Adventure game, AppSight Console Log
.asm: non-unix assembler source file, Pro/Engineer Assembly file, LICOM AlphaCAM Stone Parameter Macro, Solid Edge document
.asmx: Microsoft .NET Web Service file
.asp: active server page
.atn: Adobe Photoshop Action file
.au: Audio file, Audacity Audio block
.aud: Audio file
.avb: Inoculan Anti-Virus virus infected file, Microsoft Chat character file, Avid Bin File
.avd: Avery Label Pro Data file, DOS7 file
.avi: Audio Video Interleaved animated file (Windows Video, Quicktime, RealPlayer)
.awb: Lavasoft Ad-aware backup file, ActiveWords WordBase, Adaptive Multi-Rate Wideband ACELP codec
.awd: AWD MS Fax, Award BIOS file, AWK Language Source Code file, Artweaver Painting, FaxView document
.awe: Adobe Acrobat Bookmark XML file
.awm: Animated Works Movie, AllWebMenus, RenderWare Language Pack

When you look at a list of files you may notice that the file extensions are hidden. To find out if they are hidden right click “Start” then left click “Explore”, then click on a file fold on the left side of your screen. If you do not see file extensions they are hidden you can make then visible them by following the actions below.

Windows 98

Select “View” then “Folder Options”.  Select the ”View” tab. Scroll down to “Hide file extensions for known file types” and uncheck this box.

Windows XP

Select “Tools” then  “Folder Options”. Select the “View” tab and scroll down to “Hide file extensions for known file types” and uncheck this box. Click “Apply to All Folders”

Vista

Click on the “organize” button. Select “Folder and Search Options”.  Select the “View” tab and scroll down to “Hide file extensions for known file types” and uncheck this box. Click “Apply to All Folders”

This article has been provided to APCUG by the author solely for publication by APCUG member groups. All other uses require the permission of the author (see e-mail address above).