According to operational methodology a computer can be classified into three types Analog computers, Digital computers and Hybrid computers.
The Analog computer is obsolete nowadays. It works on continuous variables for the purpose of mathematical computation. The result given by them is only approximate since they deal with quantities that vary continuously.
A Digital computer works on the principle of binary digit system i.e. 0 to 1. It can perform complex problems and give more accurate and faster results. Hence, Digital computers are used in the field of design, research and data processing.
The Hybrid computers are a combination of Analog and Digital computers. They are also in use nowadays.