Also referred to colloquially as big iron and heavy metal.A large, expensive, and often highly redundant computer designed to support a large organization, handle intensive computational tasks, support a large number of users, and make use of large volumes of secondary storage. The largest mainframes are capable of supporting thousands of simultaneous users and use terabytes of secondary storage. Notably, mainframes are employed in a centralized computing architecture, which is opposite the distributed architecture of local area networks (LANs) and the Internet.The term originally described the main frame that contained the central processing unit (CPU) of computers in the days when all computers were heavy metal. See also Internet, LAN, minicomputer, and personal computer.