title: Why are most file extensions 3 characters or less?
body: <p>Most files I see and use end in .something, where the .something is often 3 characters. I know that some file extentions are shorter, like .py or .r, but I have never seen one longer than .exe or .jpg</p>
  
  <p>I know from this <a href="http://windows.microsoft.com/en-US/windows-vista/File-names-and-file-name-extensions-frequently-asked-questions" rel="nofollow">FAQ</a> that they can be up to 260 characters including the file's name.</p>
  
  <p>Why is the standard 3 characters?</p>