[Double-Data Rate Synchronous Dynamic Random Access Memory]
This type of memory is a SDRAM technology that is cost effective. It is able to improve the memory clock speed as it transfers the output on the rising and falling edges of the clock cycle, rather than the ordinary rising part. This means that it accesses twice as much data in once clock cycle than regular memory does.
DDR-SDRAM is measured in size in bytes, and measured in speed in hertz.