title: HTTP request header: UserAgent variable
body: <p>When sending a HTTP request, IE sends the User-Agent variable to the server. A possible value (as seen by the network debugger):</p>
  
  <blockquote>
    <p>User-Agent: Mozilla /5.0 (Compatible MSIE 9.0;Windows NT 6.1;WOW64;
    Trident/5.0)</p>
  </blockquote>
  
  <p>My question: How does IE (or any other browser) find out this variable?
  I'm asking this because when visiting some websites, this variable is different than others and I'd like to trace where the change is coming from. 'Compatibility settings' is one option, but I think there is more to it.</p>
  
  <p>Can anyone explain the process of this variable?</p>