Sweet Baby

Web proxy caches work on the same principle, but a much larger scale. Proxies serve hundreds or thousands of users in the same way; large corporations and ISPs often set them up on their firewalls, or as standalone devices (also known as intermediaries).

Because proxy caches aren’t part of the client or the origin server, but instead are out on the network, requests have to be routed to them somehow. One way to do this is to use your browser’s proxy setting to manually tell it what proxy to use; another is using interception. Interception proxies have Web requests redirected to them by the underlying network itself, so that clients don’t need to be configured for them, or even know about them.

Proxy caches are a type of shared cache; rather than just having one person using them, they usually have a large number of users, and because of this they are very good at reducing latency and network traffic. That’s because popular representations are reused a number of times.