Computers can be classified as personal computers, mini computers, mainframe computers, or super computers, though classifications are becoming blurred due to rapid technological changes. Super computers, also called monsters, are the largest, fastest and most powerful computers mainly used for complex scientific calculations in research. Mainframe computers are very large, powerful and expensive, capable of storing huge amounts of data, and are found in large organizations like banks. Mini computers had storage and processing between microcomputers and PCs, but are now outdated and rarely used.