title: What should my expires, cache-control, and pragma HTTP request header fields be set to?
body: <p>I have a website in which I update the content approximately once monthly.  When I check the HTTP request header fields, I get the following output:</p>
  
  <pre><code>Expires: Thu, 19 Nov 1981 08:52:00 GMT  
  Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0   
  Pragma: no-cache
  </code></pre>
  
  <p>My question is, given the frequency at which I update content, I am thinking about manually setting these fields to allow cache of the site.  I am using the php header(); command to do so.  </p>
  
  <p>Therefore, my question is: what should my expires, cache-control, and pragma HTTP request header fields be set to?  Also, should I be setting any other fields in addition to those?</p>