We can categorized computers in two way

1. On the basis of working principle
   1. Analog Computer: These types of computers handle continuous physical phenomena, like mechanical, electrical or hydraulic quantities. Examples: Thermometer, Speedometer, Petrol Pump Indicator, Multi-meter.
      
   2. Digital Computer: These types of computers perform calculations and logical operation. It represents the digital data or binary number system.
      
   3. Hybrid Computer (Analog + Digital): These types of computers are basically a combination of both digital and analog signals. These computers offer to solve the complex problems in cheap cost.

2. On the basis of Size
   1. Super Computer: These types of computers are very large in size and very expensive in cost. Super computers have huge capability to solve numerous amounts of mathematical calculations. But these are designed for specialized applications like, weather forecasting, military system. etc. Super computer channels all its power to executing a few programs as fast as possible.
      
   
   2. Mainframe Computer: These types of computers are also very large in size and also very expensive. In this types of computers thousands of user can use simultaneously. Generally it placed in a room which floor are made by wood and all the cable passing under the wooden floor. Mainframe computers are more powerful than super computers, when we consider the number of processes run in it. But supercomputer executes a single task faster than mainframe computer.
      
   3. Mini Computer: Mini computers are small in size and power in compare to mainframe computers but larger than macro computers. A minicomputer is a multiprocessing system which is support 4 to 200 users simultaneously.
   4. Micro Computer
      • Desktop Computer: These types of computer are actually fit on desk or table.
        
      • Laptop Computer: Laptop is a portable computer complete with an integrated screen and keyboard. It is smaller than a desktop computer and larger than a notebook computer. These types of computer placed on user lap that is why its name is laptop.
        
      • Palmtop Computer/Digital Diary /Notebook /PDAs: It is a hand-sized computer which can hold in user plum easily. It have n keyboard but it has on screen keyboard. A screen of the palmtop used as a input device as well as output device.
        
   
   5. Workstations: Workstations are generally a terminal or desktop computer in a network which has only a monitor and one or more input devices. It is connected to a server or mainframe computer.