Using cache memory is an astute way to enhance download time and free up the network. If you have this function on your browser and have not deactivated it, when you launch a request, your browser checks a directory on your hard disk to see if the HTML page has been loaded previously. If this is not the case, it carries out the request but when the result arrives, it records it on your disk at the same time as it displays it on the screen. The next time the same request is launched, the browser simply reads it on your disk. You then see the result posted up much faster than if it had covered the actual distance separating you from the server.
Recent browsers enable certain function parameters of the cache memory to be changed.
In particular, you can indicate the maximum amount of disk space it can use, or even whether the browser must check if the page in question has been changed on the server in the meantime. And of course you can always delete these files manually. Using cache memory is not the prerogative of Internet browsers. From microprocessors to operating systems, this technique is widely used. It amounts to storing closer at hand an item of information which will probably be requested again later, in order not to have to go looking for it further away more than once.