Browser cache and history test
The browser cache and history test lets you set various combinations of http headers affecting how the browser caches a web page. Here's how it works.
For each request made to the server, a counter is incremented server side. The counter value is stored in a cookie. The result is that for each request, a page is served with an incremented counter value. Now, to test whether the browser will make a request for a previously loaded page you use the "Back" button in the browser. Pages served directly from cache will have their original counter values. If the page is requested from the server, the counter will increase instead.
To test how a browser behaves for different combinations of cache related headers click through the combinations of interest — them simply press back in your browser to see which pages are reloaded by the browser.