title: Naming convention uploaded files
body: <p>On my site I let users upload files.</p>
  
  <p>If the file is valid and uploaded it is moved to a folder (using PHP).</p>
  
  <p>All users upload to the same folder.</p>
  
  <p>I think I need to rename the uploaded files.</p>
  
  <p>Is there something like a default naming convention to let users upload files with the same filename?</p>