virtual address

A virtual address is a binary number in virtual memory that enables a process to use a location in primary storage (main memory) independently of other processes and to use more space than actually exists in primary storage by temporarily relegating some contents to a hard disk or internal flash drive.

In a computer that incorporates memory management, the virtual address differs from the physical address, which is the data location on an address bus that corresponds to a particular cell of primary storage or to a particular register in a memory-mapped I/O (input/output) device.

In a computer with both physical and virtual memory, a so-called MMU (memory management unit) coordinates and controls all of the memory resources, assigning portions called blocks to various running programs to optimize system performance. By translating between virtual addresses and physical addresses, the MMU allows every running process to "think" that it has all the primary storage to itself.