Do you know that? Explain your process in simplest terms to client next

What is a cache? How it is mapped with main memory?

Cache memory: - 

The cache memory is employed in computer systems to compensate
 for the speed differential between main memory access time and processor 10gic.CPU logic
 is usually faster than main memory access time, with the result that processing speed is
 limited primarily by the speed of main memory.

 Mapping of memory:-

The basic characters tics of cache memory is its fast access time.
 Therefore, very little or no time must be wasted when searching for words in the cache. The
 transformation of data from main memory to cache memory is referred as a mapping
 process. Three types of mapping procedures are of practical interest when considering the
 organization of cache memory: Associative mapping, Direct mapping and Set-associative
 mapping.