random access memory (RAM)

Memory that has the same access time for all locations. RAM may be either static, which holds its memory so long as there is a power supply, or dynamic, which has to be refreshed by reading and rewriting the contents very frequently (about every two milliseconds). Dynamic RAM (DRAM) is more widely used than static RAM because it needs less power. Both dynamic and static RAM are volatile, i.e. the contents of it disappear when the power is switched off (hence the need for backing store in a computer).