1. A supercomputer is a computer with a high-level computational capacity compared to a general-purpose computer. The performance of a supercomputer is measured in floating-point operations per second (FLOPS) instead of million instructions per second (MIPS). As of 2015, there are supercomputers which can perform up to quadrillions of FLOPS.
2. Mainframe computers (colloquially referred to as "big iron") are computers used primarily by large organisations for critical applications, bulk data processing, such as census, industry and consumer statistics, enterprise resource planning, and transaction processing.
The term originally referred to the large cabinets called "mainframes" that housed the central processing unit and main memory of early computers. Later, the term was used to distinguish high-end commercial machines from less powerful units. Most large-scale computer system architectures were established in the 1960s, but continue to evolve.