This is a special area of very high-speed memory linked directly to the computer's central processing unit (CPU, the main processor, or chip, that runs the machine). The processor can access information in this cache much more quickly than it can get to data stored in the main memory area. The cache circuits monitor the data used by the processor, keeping a copy of the most recently and most frequently used information in the cache. Since programs are likely to access several items of related data that are near each other, the cache will even try to anticipate the processor's needs by copying data stored near the requested data in main memory. When the processor requests data from main memory, the cache first checks to see if it already has a copy, in which case the cache provides the data. Otherwise the main memory retrieves the data.