title: When to use the different log levels
body: <p>There are different ways to log messages, in order of fatality:</p>
  
  <ol>
  <li><p><code>FATAL</code></p></li>
  <li><p><code>ERROR</code></p></li>
  <li><p><code>WARN</code></p></li>
  <li><p><code>INFO</code></p></li>
  <li><p><code>DEBUG</code></p></li>
  <li><p><code>TRACE</code></p></li>
  </ol>
  
  <p>How do I decide when to use which?</p>
  
  <p>What's a good heuristic to use?</p>