Static Random Access Memory (SRAM) retains its contents by having a constant source of power applied. This differs from Dynamic Random Access Memory (DRAM) that needs to be regularly refreshed for the memory cells to maintain their state.
SRAM is faster and consumes less power than DRAM, however, because of this it is slightly more expensive.
Due to the nature of its data storage SRAM takes up more space for less memory than DRAM does. This is known as its density. DRAM can store more and is therefore more suited to low cost, high capacity systems, such as a PCs main memory.
The application of SRAM is more likely to be on the processor itself or in the form of a small but very fast cache memory.
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Next: Read Only Memory (ROM)