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 ...

Need more time to file taxes? Fill out IRS extension Form 4868 mapodile / Getty Images Taxpayers unable to file their federal income tax return by the filing deadline can apply for an extension with ...

Mac OS X computers use a default application to open every file type based on its file extension. If you don't want to use the default application when opening a file, you can select "Open With" from ...

Red Eye Rose received a file with a strange extension. She doesn’t know into what program she should load it. Neither does Windows. I doubt that anyone knows all of the file extensions used since the ...