An AND gate is a basic digital logic gate that outputs true or high only when all its inputs are true or high. It is a fundamental building block in digital circuits and is used in various applications, including computer processors and control systems. The output of an AND gate can be represented by the logical expression A AND B, where A and B are the inputs. In a typical AND gate, if both inputs are 1 (true), the output will also be 1 (true). If either input is 0 (false), the output will be 0 (false). This behavior makes AND gates essential for creating complex logical operations in computers and electronic devices.