Memory

Rom

Short for read-only memory. Computer hardware that stores programs or data that cannot be added to, modified, or deleted. ROM does not require power to maintain its contents, and is often used to save instructions that enable the computer's operating system to communicate with other hardware.

Ram

Short for random access memory.  The main memory of a computer, in which data can be stored or retrieved from all locations at the same (usually very high) speed. More RAM in a computer equals to having more space to put programs on and have multiple running at the same time.