Windows File Associations
File associations allow the Windows operating system to "associate" specific file extensions with specific applications. This is how Windows decides which program to use to when you choose to do something with a file, like open or print it.
For example, if you are working in Microsoft Excel, and you save an Excel file, you know that the file name will be saved with an extension of .xls at the end of it.
That file extension of .xls tells Windows that the file can be opened, saved or printed (i.e., the file association is with) Microsoft Excel.
If the file has already been opened and saved with Excel, Windows XP can figure out it’s an Excel file, even if you change the file extension.
But if you receive an new Excel file from another source, say as an email attachment, and that file has another file extension, or no file extension at all, Windows may not be able to determine that the file is an Excel file. And if windows can't, the file won't open unless you change the file name to include the .xls extension. This is why it’s important to name your files with the correct file extensions.
Fixing File Association Errors in Windows XP
Windows keeps a list of file extensions and file associations within itself. You can see them by following these steps:
- Open Windows Explorer by right clicking on the Start button and then clicking on Explore.
- Click on the Tools menu, and then Folder Options.
- Click on the File types tab.
If a specific file association gets changed or deleted, and you try to open a file that has that extension, you will get Windows errors that say essentially "this file has no program associated with it".
In other words, if I go into the File Extensions table in Windows Explorer and I delete the association between the (fictitious) .ttt extension and the MS Word program, the next time I try to double click on a .ttt file to open it, Windows will show me this error:
To fix this kind of error, you choose "Select the program from a list" and click OK.
Then on the next dialog box, find the program that should be associated with the file and click on it.
If the program you want to choose is not in the list offered, you may have to click Browse button, and browse through the C:Program Files directory for the program folder, and then within that program folder for the .exe file.
Once you have chosen the appropriate file association, make sure that you check off the box that says "Always use the selected program to open this kind of file" to make it a permanent choice when you click OK.
You can also change the program that launches when you double click on a certain file. For example, if you want all of your .txt files to open in Word instead of in Notepad, change the .txt association to launch Word instead. Here’s a step by step article that includes some steps on how to do this.
Some file extensions should not be changed. If the file has an .exe, .com or .bat extension, don’t change it. These are "executable" programs and they won’t launch if you change that extension.
Fixing File Associations in Vista
The File Associations area in Vista is kind of buried so I'm including those steps here as well.
- Click on the round windows button on the bottom left hand corner of your screen.
- Click on the Control Panel button
- On Control Panel, click on Programs
- Under Programs, click on Default Programs
- Under Default Programs, click on Associate a file type or protocol with a program
- Find the file extension you need to fix in the list presented. You may have to click in the list first and then scroll down
- Highlight the file extension and then click the Change Program... button on the top right
- Choose one of the programs recommended and then click OK.
- Then click Close and use the red x to close out of any other windows you opened.
Common File Extensions
Here’s a list of some common and not so common file extensions and the programs that create them:
| .accdb || Office Access 2007 database file format |
| .accdt || Access Database Templates |
| .ace || Compressed file archive |
| .ai || Adobe Illustrator graphics |
| .ani || Animated cursor |
| .arj || Compressed file archive - ARJ archiver |
| .asp || ASP script or page (Active Server) |
| .aup || Audacity project file |
| .avi || Audio Video Interleave movie |
| .bak || Backup file |
| .bat || Batch file (executable) |
| .bc! || Bittorrent unfinished download file |
| .bik || BINK video file |
| .bin || Binary file |
| .bin || Macbinary II encoded file |
| .bmp || Bitmap graphics file |
| .bmp || Standard Windows Bitmap image (also OS/2) |
| .cab || Windows Cabinet Compressed Archive |
| .cbr || Comic Book Archive file or ComicBook Reader File |
| .cdr || CorelDRAW vector image |
| .cfg || Configuration files |
| .cr2 || Canon digital camera RAW image format version 2 |
| .crw || Canon digital camera RAW image format |
| .css || Cascading Style Sheets file |
| .ctt || Messenger Contact List |
| .dao || Disk at Once CD/DVD Image |
| .dat || Binary or text data file |
| .dbf || Database file |
| .dcr || Kodak Digital Camera Raw Image Format |
| .dib || Device-Independent Bitmap Graphic |
| .dll || Dynamic Link Library file |
| .dmp || Windows dump file |
| .doc || Microsoft Word file |
| .doc || Microsoft Office Word document |
| .docx || Microsoft Word 2007 file |
| .docx || Microsoft Word 2007 XML based document file format |
| .dot || Microsoft Word template |
| .dot || MS Word Document Template |
| .dotm || Word 2007 Macro-Enabled Template |
| .dotx || Microsoft Word 2007 template |
| .dotx || Word 2007 Template |
| .dwg || AutoCAD Drawing |
| .dxf || Drawing Exchange Format |
| .eps || Adobe Illustrator text and graphics (Encapsulated PostScript) |
| .exe || Executable file |
| .fil || Vault file of AVG antivirus |
| .fla || Adobe Flash file |
| .gif || GIF graphics file |
| .gif || Graphics interchange file format |
| .htm || Web page - HTML file |
| .html || Web page file - Hypertext Markup Language |
| .ico || Icon file |
| .ifo || DVD movie information file |
| .img || Bitmap Graphic (several programs) |
| .img || CloneCd image file |
| .ind || Adobe InDesign graphics document file |
| .jpeg || JPEG image, picture file format |
| .jpg || JPEG graphics file |
| .jpg || JPEG bitmap image file format |
| .mdb || Microsoft Access database |
| .mov || Apple QuickTime Movie file, standard Macintosh video format |
| .mp3 || Compressed audio, music file |
| .mp4 || MPEG-4 file format |
| .mpg || MPEG 1 video file format |
| .mpp || Microsoft Project file extension |
| .msi || Microsoft Windows Installer installation package file |
| .nrg || Nero-Burning ROM CD or DVD image file |
| .ods || OpenOffice org Calc Spreadsheet file |
| .odt || OpenOffice org Writer text document |
| .ost || Outlook folder file |
| .otf || Open type font file format |
| .pcd || Kodak Picture CD multiresolution Image |
| .pcx || PC Paintbrush Bitmap |
| .pdb || Palmpilot Database File |
| .pdf || Adobe Acrobat Portable Document File |
| .php || PHP script, page |
| .php3 || PHP version 3 script file |
| .png || Portable (Public) Network Graphic |
| .potx || PowerPoint 2007 XML Template |
| .pps || Microsoft Powerpoint Slide Show |
| .pps || PowerPoint Slideshow |
| .ppsm || PowerPoint 2007 Macro-Enabled XML Show |
| .ppsx || PowerPoint 2007 XML Show |
| .ppt || Microsoft Powerpoint file |
| .ppt || PowerPoint Presentation file format |
| .pptx || PowerPoint 2007 Presentation |
| .prt || PTC Pro/Engineer Part file |
| .prt || SolidWorks Part file |
| .psd || Adobe Photoshop Document |
| .psd || Adobe Photoshop graphics |
| .psp || Paint Shop Pro image |
| .pst || Outlook 2003 personal folder |
| .pub || Microsoft Publisher file |
| .rss || Really Simple Syndication - RSS file format |
| .rtf || Rich Text Format document |
| .srt || Movie subtitle file format |
| .swf || ShockWave Flash, Animated vector format for the Internet |
| .sxc || OpenOffice |
| .sys || System file |
| .tif || Aldus Tagged Image File Format (TIFF) bitmap image |
| .tmp || Temporary file |
| .tmp || Temporary file |
| .torrent || BitTorrent information file |
| .ttf || TrueType Font |
| .txt || Common text file |
| .vob || MPEG-2 movie |
| .vxd || Microsoft Windows virtual device driver, 32 bit |
| .wav || WAVe PCM Sound, standard Windows sound format |
| .wba || WindowBlinds Desktop visual style |
| .wdb || Microsoft Works database |
| .wma || Windows Media Audio |
| .wmf || Windows Metafile |
| .wmv || Windows Media Video |
| .wpd || Corel WordPerfect document |
| .wpl || Windows Media Player Playlist |
| .wps || Microsoft Works document |
| .wri || Windows Write Document |
| .xls || Microsoft Excel spreadsheet file |
| .xls || Microsoft Office Excel spreadsheet |
| .xlsm || Excel 2007 XML Macro-Enabled Workbook |
| .xlsx || Excel 2007 XML Workbook |
| .xlt || Microsoft Excel spreadsheet template |
| .xltx || Excel 2007 file |
| .xml || XML document |
| .xpi || Firefox browser extension |
| .zip || Compressed ZIP archive file and compressed folder |
| .zix || WinZix compressed archive file |
Well, I hope that helps you understand Windows file associations a little more.
Done with File Associations, take me back to Computer Tips