Cache is essentially, a chunk of very high speed memory available exclusively to the processor for storing very commonly accessed data. When the CPU is looking for an instruction/data and it is found in the cache, that is known as a cache hit. There are several types of cache:
* L1 Data and L1 Trace (collectively known as L1), this type of cache is usually quite small (small on AMD processors and tiny on Intel) and is the first place the CPU looks for information. Due to its small size and the variance of instructions/data available, cache hits in L1 are not a performance bottleneck
* L2 cache is the most marketed cache and is big enough to actually influence the performance of the processor with budget processors cheaping out on the amount of L2 cache available. Although "the more L2 cache available, the better", also note that the more cache they cram onto a processor, the slower and less efficient it becomes and the more the cache becomes dependent on optimizations designed to improve cache hits
* L3 cache is essentially, another type of L2 (but slower still) and is reserved for storing a (relative) whack of data somewhat close to the CPU. L3 cache was available only on select models of the Intel Pentium4 Extreme Edition and has since been discontinued in favor of a larger L2 cache.
