title: What exactly does the timeZone option do in Intl.DateTimeFormat()
body: <p>I have difficulties to understand what the <code>timeZone</code> option in the <code>Intl.DateTimeFormat()</code> method exactly does. I could not find an in-depth resource on this, yet. Any explanation would be much appreciated.</p>
  
  <p><em>Background: We need to display the timestamp of a backend server on the frontend and had some issues with the timezone offset. At the moment, I believe the solution to display the correct time depending on the local client time is the following:</em> </p>
  
  <pre><code>Intl.DateTimeFormat('en-GB', {
            hour: 'numeric',
            minute: 'numeric',
            second: 'numeric',
            timeZone: 'GMT'
          }).format(timestamp)}
  </code></pre>
  
  <p><em>I do not fully understand, why I need to pass the option timeZone: 'GMT' for "Greenwich Mean Time' to get the correct time on the frontend.</em></p>