Supercomputers are large machines designed for problems whose solution is limited by the number of calculations involved. Such problems are regularly encountered in fields such as weather prediction, simulation of explosions, drug design, and many other fields.
Seymour Cray is the legendary designer of a range of supercomputers, first for Control Data Corporation (CDC) and later for his own firm, Cray Research, Cray Computer Corporation and SRC Computers. The CRAY-1, introduced in 1976, became the icon of the supercomputer world with its unique design (often called the most expensive love seat ever made).
Supercomputers were the economical way to solve large problems until the advent of large parallel machines based on simple processors such as those found in the personal computer. Even today there are cost effective supercomputers being produced for a certain class of problem, but they are no longer as essential as they once were.