title: Understanding the timing values from Charles debugging proxy
body: <p><img src="https://i.stack.imgur.com/Q60RP.png" alt="enter image description here"></p>
  
  <p>This image from Charles shows some pretty interesting information:</p>
  
  <ul>
  <li>Duration</li>
  <li>Request Duration</li>
  <li>Response Duration</li>
  <li>Latency</li>
  </ul>
  
  <p>I'd like to better understand what these terms actually mean.</p>
  
  <p>ie.,  How does Charles measure the request duration?  (In the course of a HTTP transaction, this is the time from when-to-when?)  Likewise for response.</p>
  
  <p>Also, <code>request + response != Duration</code>.  Is the remainder server-side processing time?</p>
  
  <p>What is Latency a measure of here?</p>