title: What is Auth'n'auth?
body: <p>Requesting my keys on developer.eBay, I see a message that invites me to enable OAuth. But the message also speaks about <code>Auth'n'auth</code>.</p>
  
  <p>Searching for it on Google doesn't give me any information about what this is, so I'm asking here.</p>
  
  <p>The complete message given to me by eBay is:</p>
  
  <blockquote>
    <p>To use eBay's latest security features, add OAuth security to your
    keys. These keys will support both Auth'n'auth and OAuth.</p>
    
    <p>For keys with multiple redirect URLs go to the Tokens page and enable
    one redirect URL for OAuth only. All redirect URLs will continue to
    support Auth'n'auth.</p>
  </blockquote>