Cache is basically integrated memory, Cache usually works at the same speed as the piece of hardware it is attached to. For example the 2MB Cache on the 3.2GHz P4 EXTREME processor works at a much faster speed than the mainboard RAM.
Good explaination I read once:
Compared to the human brain the computer works like this.
CPU = Brain power
CPU Cache = Awareness
RAM = Short Term memory
Hard Drive = Long term memory
You think about yourself, your awareness if how you keep things in motion, walking 1 leg after the other.
Short Term memory, like when you are in a classroom and your teacher says
18 x y = 1008
y = 56
You don't have to work it out again if the teacher asks you what y = ?, you normally (
) remember, and it is quicker than your long term memory.
Long Term is trying to remember an old school mate's name when you are drunk but you can't quite remember it but he remembers yours!