Front end users - cachable pages

[calguy1000]

Any page that changes its content or behavior based on the user that browses to it (anonymous user, known user, admin user), where they come from, or when they browse (i.e: if you have content that changes at various times of the day, or day of the week) cannot be cached. The system has to decide what to display, or where to redirect to for each request.

These pages cannot be cached in HTML on the server (though possibly some portions of them could be). and cannot be cached on the browser. Of course, this is not optimal for website performance, user experience or server load. This is one of the reasons facebook has massive server farms

Static pages are the best, and allowing the browser to cache as much as possible (so that repeated requests from the same user don't have to download 'everything' again.).