Stands for Synchronous Dynamic Random Access Memory. SDRAM is a faster version of DRAM, which is the type of memory chips that have been used in most computing equipment for the past several years. SDRAM began to appear in 1997 and can synchronize itself to the bus speed of the computer, which is what makes it so much faster than standard Dynamic RAM. There are a number of other subtypes of RAM with different names and different properties. More are being developed all the time.