title: What is Cache-Control: private?
body: <p>When I visit <a href="http://chesseng.herokuapp.com" rel="noreferrer">chesseng.herokuapp.com</a> I get a response header that looks like</p>
  
  <pre><code>Cache-Control:private
  Connection:keep-alive
  Content-Encoding:gzip
  Content-Type:text/css
  Date:Tue, 16 Oct 2012 06:37:53 GMT
  Last-Modified:Tue, 16 Oct 2012 03:13:38 GMT
  Status:200 OK
  transfer-encoding:chunked
  Vary:Accept-Encoding
  X-Rack-Cache:miss
  </code></pre>
  
  <p>and then I refresh the page and get</p>
  
  <pre><code>Cache-Control:private
  Connection:keep-alive
  Date:Tue, 16 Oct 2012 06:20:49 GMT
  Status:304 Not Modified
  X-Rack-Cache:miss
  </code></pre>
  
  <p>so it seems like caching is working. If that works for caching then what is the point of <strong><em>Expires</em></strong> and <strong>Cache-Control:max-age</strong>. To add to confusion, when I test the page at <a href="https://developers.google.com/speed/pagespeed/insights" rel="noreferrer">https://developers.google.com/speed/pagespeed/insights/</a> it tells me to "Leverage browser caching".</p>