Can somebody tell me what Cache memory is?

[hellemnicole]

I know what RAM is, but what is cache? How is it important? I was trying to buy a computer, and somebody told me that it should have as much cache as possible. But I don't know what that is.

[marcob]

A CPU cache is a type of memory used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory llocations. As long as most memory accesses are to cached memory locations, the average latency of memory accesses will be closer to the cache latency than to the latency of main memory.