The document classifies computers into three main categories:
1. Based on operating principles - analog computers represent data as continuous signals while digital computers store and process data digitally.
2. Based on applications - general purpose computers can work in all environments while special purpose computers can only perform specific tasks.
3. Based on size and capability - microcomputers are designed for individual use, mini computers can handle more data/input/output than microcomputers, and mainframe/super computers are very large and fast for complex operations.