title: Clock skew and tokens
body: <p>I need help to understand how clock skew works. We define clock skew to deal with time variation between two parties. But, my confusion is:</p>
  
  <ol>
  <li>we have all information such as token created time and expiration time in the token itself</li>
  <li>tokens can be validated</li>
  <li>tokens are created on the server</li>
  </ol>
  
  <p>So, why do we need clock skew? Can anyone give me the example for how it works and in which scenarios it can cause problems or benefits?</p>