Memory refresh is a background maintenance process required during the operation of semiconductor dynamic random-access memory (DRAM), the most widely used type of computer memory, and in fact is the defining characteristic of this class of memory.
A refreshing circuit is required in dynamic random-access memory (DRAM). DRAM is a type of volatile computer memory that stores each bit of data in a separate capacitor within an integrated circuit. The stored charge in these capacitors tends to leak over time, and without periodic refreshing, the information in the memory cells would be lost.