A computer carries out all operations internally by means of combinations of signals passing through standard blocks of built-in circuits known as logic gates. In other words, a logic gate is an electronic circuit that operates on one or more input signals to produce standard output signals. These logic gates are the building blocks of electronic circuits in a computer.
Combinations of multiple logic gates of different types are often used to build electronic circuits in computers. Out of many types of logic gates available, we shall study here only some of the most important ones. These are sufficient to introduce the concept of electronic logic circuit design with the use of logic gates.