Basics of Caches:
"The caches are situated on basis of blocks, the shortest amount of data which may be copied between 2 adjacent levels at a time.
"If requested data by the processor is present in some the upper level block
Then it is known as a hit.
"If data is not found in the upper level then this request is called a miss and the data is retrieved from the lower level in the hierarchy.
"The portion of memory accesses found in the upper level is known as a hit ratio.
"The storage, which takes profit of locality of accesses, is known as cache