XOR gate
The XOR gate (sometimes EOR gate, or EXOR gate) is a digital logic gate that implements an exclusive or; that is, a true output (1) results if one, and only one, of the inputs to the gate is true (1). If both inputs are false (0) or both are true (1), a false output (0) results. Its behavior is summarized in the truth table shown on the right. A way to remember XOR is "one or the other but not both". It represents the inequality function, i.e., the output is HIGH (1) if the inputs are not alike otherwise the output is LOW (0).
This Function is addition modulo 2. As a result, XOR gates are used to implement binary addition in computers. A half adder consists of an XOR gate and an AND gate.
Symbols
There are two symbols for XOR gates: the 'military' symbol which was originally developed in America and the 'rectangular' symbol, which was originally British. For more information see Logic Gate Symbols.
The XOR gate with inputs A and B implements the logical expression 
.
