A file extension, or file name extension, is the letters immediately shown after the last period in a file name. For example, the file extension.txt has an extension of .txt. This extension allows the ...

BearPup sometimes wants to open a file in one program, and other times open it in another. He asked the Answer Line forum for an easy way to do this. Windows uses a file’s extension–the part of the ...

In the Mac OS it is possible to change the default program the operating system will use to open a file when you double-click on it. After you have changed this file association, though, you may want ...