Definition: mass storage
Permanent peripheral storage, which is typically a hard disk drive, solid state drive (SSD) or USB drive. "Mass" is an old term that refers to large amounts of permanent storage in contrast with the smaller amount of "RAM" or "main memory," which is the computer's temporary workspace (see memory). See flash memory, USB drive, magnetic disk, optical disc and magnetic tape.
Mass Storage on a Deck of Cards
In the 1960s, a roomful of these Card Random Access Memory (CRAM) units provided 176 megabytes of direct access mass storage, a huge capacity for that era. See CRAM for more details. (Image courtesy of NCR Corporation.)