Logic gate

Definition
A logic gate is

"a fundamental building block of a system. Gates typically have two to four inputs and produce one input. These circuits are called logic gates because they compute simple functions used in logic. For example, an AND gate takes two inputs (either 1s or 0s) and returns 1 if both are 1s and 0 if either is 0. A NOT gate has only one input and returns 1 if the input is 0 and 0 if the input is 1."