Static Random Access Memory (SRAM) is a type of semiconductor memory where the word static indicates that, unlike dynamic RAM (DRAM), it does not need to be periodically refreshed, as SRAM uses bistable latching circuitry to store each bit. SRAM is a volatile memory in that data is eventually lost when the memory is not powered. Common types of SRAM are Asynchronous SRAM, DDR (Double Data Rate) SRAM, QDR (Quad Data Rate) SRAM, ZBT (Zero Bus Turnaround).