The ability to store information is vital for the efficient operation of computers and for the operation of other activities that depend on the computer (maintenance of a payroll, for example). Data storage must be efficient, safe and enable swift and correct retrieval of the data. Advances in data storage technology have made the storage of large volumes of data possible. Magnetic hard-disk drives, tapes, optical storage such as CD- and DVD-ROMs, and floppy disks are all forms of data storage.

The first hard disk—the Random Access Method of Accounting and Control (RAMAC)--was introduced by the IBM Corporation in 1956. The RAMAC drive consisted of 50 aluminum plates, each 24 inches in diameter. The drive, which could store five million characters of information, weighed almost one ton. Since then, hard drives have decreased to hand-held size and their storage capacity has increased by orders of magnitude...