The basic switching circuits or gates used in digital computers and other digital electronic devices. The output signal, using a binary notation, is controlled by the logic circuit in accordance with the input system. The three basic logic circuits are the AND, OR, and NOT circuits. The AND circuit gives a binary 1 output if a binary 1 is present on each input circuit; otherwise the output is a binary 0. The OR circuit gives a binary 1 output if a binary 1 is present on at least one input circuit; otherwise the output is binary 0. The NOT circuit inverts the input signal, giving a binary 1 output for a binary 0 input or a 0 output for a 1 input.

Often these basic logic circuits are used in combination, e.g. a NAND circuit consists of NOT+AND circuits. In terms of electronic equipment, logic circuits are now almost exclusively embodied into integrated circuits.