There are Two types of Computer.

Digital Computer and Analog Computer.

A digital computer uses distinct values to represent the data internally. All information are represented using the digits Os and 1s. The computers that we use at our homes and offices are digital computers.

Analog computer is another kind of a computer that represents data as variable across a continuous range of values. The earliest computers were analog computers.

Analog computers are used for measuring of parameters that vary continuously in real time, such as temperature, pressure and voltage. Analog computers may be more flexible but generally less precise than digital computers. Slide rule is an example of an analog computer.

This book deals only with the digital computer and uses the term computer for them.