The time taken to retrieve an item of information from storage. The access time may be counted in nanoseconds for a semiconductor device, in milliseconds for a magnetic disk, or in minutes if the file containing the required data is on magnetic tape.
In the case of disk storage, the access time is the average time taken for a disk drive to provide the first byte of data, measured from the time the host issues a read command. To a good approximation, the average access time is the sum of the average seek time, the command overhead, and the average latency. See also memory hierarchy.