SRAM

Static Random Access Memory refers to a type of RAM (Random Access Memory) which does not need to be periodically refreshed, and is therefore stable so long as power is supplied to its circuit. SRAM is faster than its common counterpart, DRAM, and also more expensive. Because it is capable of a stable "idling" state, SRAM is considerably more efficient in its power draw compared to DRAM.

In microcontrollers and embedded computing, SRAM is used as the memory medium for the internal CPU cache, as in the Atmel ATmega328, which powers newer Arduino boards.