The term memory identifies data storage that comes in the form of chips , and the word storage is used for memory that exists on tapes or disks . Moreover, the term memory is usually used as a shorthand for physical memory, which refers to the actual chips capable of holding data.
Some computers also use virtual memory , which expands physical memory onto a hard disk .
Every computer comes with a certain amount of physical memory, usually referred to as main memory or RAM . You can think of main memory as an array of boxes, each of which can hold a single byte of information. This is in contrast to ROM , which permits you only to read data. Most RAM is volatile, which means that it requires a steady flow of electricity to maintain its contents. As soon as the power is turned off, whatever data was in RAM is lost.