Random-access memory (
RAM ) is a form of
computer data storage. A random-access memory device allows
data items to be accessed (
read or written) in almost the same amount of time irrespective of the physical location of data inside the memory. In contrast, with other direct-access data storage media such as
hard disks,
CD-RWs,
DVD-RWs and the older
drum memory, the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement.