so i have set up apache serving my php pages.

i read about squid but don't understand why/how i should use it to speed up my web server.

from what i've learned squid is located in same network (or another) and caches content requested by the web browsers, and then when another web browser wants a same page, squid returns that page cached locally, so it never sends a request to the apache server (faster response time for the client, and reduced load for the server). so it seems that squid is for the client side (web browser), and has nothing to do with the server side (apache).

but then some people tell others how they have speeded up apache using squid. so im confused. could squid be used on the server side too? and how will it work?