Mainframe computer is the largest type of computer. Mainframes can process billions of calculations per second and can manage huge amounts of information. Most mainframes are housed in large cabinets that remain in fixed locations. Users access the mainframe through other computers, which may be located far from the mainframe.
Until the advent of the personal computer (a smaller computer used by one person), mainframes were the most common type of computer. Personal computers and other smaller computers now perform many operations once done by mainframes. Mainframes continue to handle the most complex types of computer operations, including advanced scientific calculations and the storage of vast amounts of data.
On a large mainframe, hundreds of people may be logged on (running programs) at one time. The use of a single powerful computer by many users at once is called time-sharing. The mainframe appears to run many programs at the same time. However, it actually switches rapidly from program to program, doing a bit of work on one, then hurrying on to another.
Governments, corporations, and other large organizations find mainframes essential. No other computer could handle their huge databases of information, such as tax records, payrolls, and inventories. No other computer could effectively manage computer and telecommunications networks.
