Windows associates data files with applications so that the appropriate program launches automatically when the icon or name of the data file is clicked. For example, if a GIF image is associated with the Windows Picture and Fax Viewer, whenever a file with the .GIF extension is selected, the Windows Picture and Fax Viewer will launch and open that file.
This procedure simply saves a step. You can always launch the program first and then select which data files to open.
All major file types are listed and pre-associated with the applications that come with Windows, but you can choose another program to open them. If a particular file type is not in the list, you can enter it and then associate it.
Change Association This Time
Sometimes you may want to open a data file with a different program. To open a file by choosing the application, see Win Open With
Change Association Permanently
If the program is not in the list, you must know the name of the executable program file (.EXE extension) and its folder location (path) on the hard disk (see Win folder organization
Windows 7 and 10
To associate the same data files all the time to one program, do the following:
1. Start menu/Control Panel.
2. Select Default Programs.
3. Select Associate a file type or protocol...
4. Highlight a file type and select Change Program.
File Associations in Windows Vista, 7 and 8
Windows Vista, 7 and 8 are more helpful than previous Windows versions, because they describe both the file and the program.
File Associations in XP
The XP dialog does not describe the purpose of the file type.
Creating Brand New Associations
You can associate an application with a file type that has not been opened or associated before.
Windows 7 and 10
To associate a new file type, do the following:
1. Launch Explorer.
2. Right click the file you want to associate and select Properties.
3. Select Change on Opens With line.
4. Select a program from a list.