File Associations

Windows "associates" file types with a program to open or run that type of file.  The association is linked to the the "extension" of the file name (the last 3 characters after the dot) - for example, any file name ending with ".txt" will be associated with Notepad.exe and when you double-click on the file "contacts.txt" for example - it will open within Notepad so that the user can read or edit the contents.

The file associations are stored within the Registry.

Viewing all File Associations

Open Explorer, select Tools/Folder Options/File Types

Re-Associating Files

Files usually have default associations.  For example, a file ending with "htm" will typically be associated with Internet Explorer.  However, you may want all of your htm files to open up with FrontPage if you do a lot of editing and web page development. 

Method 1

Win 98/ME users have an out that Win 95 users don't. Find a program that has an incorrect file association with it in Explorer. Click it once to select it, then hold down the Shift key while right-clicking it. Choose Open With. Select the correct program, check the "Always use this program to open this type of file" box and click on OK. 

With WinXP it is even easier.  Right-click any file, select "Open With  .  .  .  Choose Program . . . and select the program you wish to use, and again select the "Always use this program to open this type of file" box and click on OK.

Method 2

Open Explorer, select Tools/Folder Options/File Types.

From there you can click on any file type, and it's association will be shown as "actions" such as Open, or "Play".  You can edit these actions, changing the associated program used to open the file.  For certain types of associations, such as wav files associated to mplayer.exe, you can also add switches to the run line to make sure the file actually plays after opening (add "/play" without the quotes to the end of the line) or the application closes after playing the file (add "/close" to the end)