In computer architecture, the memory hierarchy is a concept used to discuss performance issues in computer architectural design, algorithm predictions, and lower level programming constructs involving locality of reference. The memory hierarchy in computer storage separates each of its levels based on response time.

Memories are closer to the top tend to be smaller in size. However, these smaller memories have better performance and thus a higher cost (per bit) than memories found lower in the pyramid.

The numbers given to the left of the pyramid indicate typical access times.This is drawn as a pyramid to help indicate the relative sizes of these various memories.

Hence, authors choose to represent it as a pyramid.