title: How do different browsers handle caching for static content without an Expires Header?
body: <p>After running the <a href="http://developer.yahoo.com/yslow" rel="nofollow noreferrer">YSlow plugin</a> on a site, I saw that one of the <a href="http://developer.yahoo.com/performance/rules.html#expires" rel="nofollow noreferrer">recommendations</a> was to add far future expires headers to the scripts, stylesheets, and images.</p>
  
  <p>I asked a <a href="https://stackoverflow.com/questions/865252/add-expires-or-cache-control-header-to-static-content-in-iis">different question</a> about how to set this up in IIS, but I am actually just curious about how each browser behaves.  </p>
  
  <p>I have read that IE will cache items per browsing session, so once you reopen the site after closing the browser, it will need to reload all of the content.  I believe that Firefox will go ahead and set a expiration date on its own.  I have also heard that IE does not cache at all when connecting over HTTPS.  I am not sure if these are at all accurate, though, and was wondering if someone could clear up any misconceptions I may have.  Thanks!</p>