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:

  1. Open Windows Explorer by right clicking on the Start button and then clicking on Explore.
  2. Click on the Tools menu, and then Folder Options.
  3. 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:

File Association 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.

File Association list

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.

  1. Click on the round windows button on the bottom left hand corner of your screen.
  2. Click on the Control Panel button
  3. On Control Panel, click on Programs
  4. Under Programs, click on Default Programs
  5. Under Default Programs, click on Associate a file type or protocol with a program
  6. 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
  7. Highlight the file extension and then click the Change Program... button on the top right
  8. Choose one of the programs recommended and then click OK.
  9. 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:


Office Access 2007 database file format


Access Database Templates


Compressed file archive


Adobe Illustrator graphics


Animated cursor


Compressed file archive - ARJ archiver


ASP script or page (Active Server)


Audacity project file


Audio Video Interleave movie


Backup file


Batch file (executable)


Bittorrent unfinished download file


BINK video file


Binary file


Macbinary II encoded file


Bitmap graphics file


Standard Windows Bitmap image (also OS/2)


Windows Cabinet Compressed Archive


Comic Book Archive file or ComicBook Reader File


CorelDRAW vector image


Configuration files


Canon digital camera RAW image format version 2


Canon digital camera RAW image format


Cascading Style Sheets file


Messenger Contact List


Disk at Once CD/DVD Image


Binary or text data file


Database file


Kodak Digital Camera Raw Image Format


Device-Independent Bitmap Graphic


Dynamic Link Library file


Windows dump file


Microsoft Word file


Microsoft Office Word document


Microsoft Word 2007 file


Microsoft Word 2007 XML based document file format


Microsoft Word template


MS Word Document Template


Word 2007 Macro-Enabled Template


Microsoft Word 2007 template


Word 2007 Template


AutoCAD Drawing


Drawing Exchange Format


Adobe Illustrator text and graphics (Encapsulated PostScript)


Executable file


Vault file of AVG antivirus


Adobe Flash file


GIF graphics file


Graphics interchange file format


Web page - HTML file


Web page file - Hypertext Markup Language


Icon file


DVD movie information file


Bitmap Graphic (several programs)


CloneCd image file


Adobe InDesign graphics document file


JPEG image, picture file format


JPEG graphics file


JPEG bitmap image file format


Microsoft Access database


Apple QuickTime Movie file, standard Macintosh video format


Compressed audio, music file


MPEG-4 file format


MPEG 1 video file format


Microsoft Project file extension


Microsoft Windows Installer installation package file


Nero-Burning ROM CD or DVD image file


OpenOffice org Calc Spreadsheet file


OpenOffice org Writer text document


Outlook folder file


Open type font file format


Kodak Picture CD multiresolution Image


PC Paintbrush Bitmap


Palmpilot Database File


Adobe Acrobat Portable Document File


PHP script, page


PHP version 3 script file


Portable (Public) Network Graphic


PowerPoint 2007 XML Template


Microsoft Powerpoint Slide Show


PowerPoint Slideshow


PowerPoint 2007 Macro-Enabled XML Show


PowerPoint 2007 XML Show


Microsoft Powerpoint file


PowerPoint Presentation file format


PowerPoint 2007 Presentation


PTC Pro/Engineer Part file


SolidWorks Part file


Adobe Photoshop Document


Adobe Photoshop graphics


Paint Shop Pro image


Outlook 2003 personal folder


Microsoft Publisher file


Really Simple Syndication - RSS file format


Rich Text Format document


Movie subtitle file format


ShockWave Flash, Animated vector format for the Internet




System file


Aldus Tagged Image File Format (TIFF) bitmap image


Temporary file


Temporary file


BitTorrent information file


TrueType Font


Common text file


MPEG-2 movie


Microsoft Windows virtual device driver, 32 bit


WAVe PCM Sound, standard Windows sound format


WindowBlinds Desktop visual style


Microsoft Works database


Windows Media Audio


Windows Metafile


Windows Media Video


Corel WordPerfect document


Windows Media Player Playlist


Microsoft Works document


Windows Write Document


Microsoft Excel spreadsheet file


Microsoft Office Excel spreadsheet


Excel 2007 XML Macro-Enabled Workbook


Excel 2007 XML Workbook


Microsoft Excel spreadsheet template


Excel 2007 file


XML document


Firefox browser extension


Compressed ZIP archive file and compressed folder


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