The page always displays faster when you hit your Back button because it is coming from your machine, not the original server. To cache Web pages remotely means to store them on your ISP's computer. The practice is widespread because it speeds delivery to you and reduces the ISP's bandwidth usage. Non-U.S. universities use a cache like a reserve book collection to also reduce telephone charges. From the orginal website's point of view, caching is a problem only because it causes the visits and visitors to be undercounted .
Hits are every transaction.
Requests are successful hits. The browser looks in your hard drive's cache for the .htm file and for any image, script, or other files embedded in it. If the local timestamp is the same, the browser displays the page off your local cache. If the files aren't in your local cache, the browser looks to any caches at the gateway where your local network or your service provider connects to the Internet. If the files aren't in one of those caches, only then does the browser make its request to the server.