There are several ways to classify computers. According to purpose, they can be general purpose computers that can perform many tasks, or special purpose computers designed for a single task. Based on processing, they are analog computers that use physical variables, digital computers that use binary numbers, or hybrid computers that combine analog and digital. Classification by capacity includes microcomputers like PCs, workstations with more power, minicomputers for limited applications, mainframe computers shared by users, and supercomputers for complex calculations.