<Tr> <Th> Date invented </Th> <Td> 24 December 1954; 63 years ago (1954 - 12 - 24) </Td> </Tr> <Tr> <Th> Invented by </Th> <Td> IBM team led by Rey Johnson </Td> </Tr> <P> A hard disk drive (HDD), hard disk, hard drive or fixed disk is a data storage device that uses magnetic storage to store and retrieve digital information using one or more rigid rapidly rotating disks (platters) coated with magnetic material . The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces . Data is accessed in a random - access manner, meaning that individual blocks of data can be stored or retrieved in any order and not only sequentially . HDDs are a type of non-volatile storage, retaining stored data even when powered off . </P> <P> Introduced by IBM in 1956, HDDs became the dominant secondary storage device for general - purpose computers by the early 1960s . Continuously improved, HDDs have maintained this position into the modern era of servers and personal computers . More than 200 companies have produced HDDs historically, though after extensive industry consolidation most current units are manufactured by Seagate, Toshiba, and Western Digital . HDD unit shipments and sales revenues are declining, though production (exabytes per year) is growing . Flash memory has a growing share of the market for secondary storage, in the form of solid - state drives (SSDs). SSDs have higher data - transfer rates, higher areal storage density, better reliability, and much lower latency and access times . Though SSDs have higher cost per bit, they are replacing HDDs where speed, power consumption, small size, and durability are important . </P>

Where is the data stored on a hard drive