A file extension is nothing more than the last characters after the period in the name of a file. FILExt is a database of file extensions and the various programs that use them. If you know the file extension you want to learn about simply enter it into the search box on the left and click on the Search button. If it's in any of the FILExt databases the data we have on that file extension will be shown on a results page. If it's not in any of the databases you will be given a link to a page with hints on how to do further research.