Exclusive or, or exclusive disjunction, abbreviated as XOR, is a logical operator with the following truth table:

FFF
FTT
TFT
TTF

Symbols used to represent exclusive or including (\oplus) and (\veebar).

One way to understand the xor operator is “addition modulo 2”.

XOR in Cryptography

see also: XOR cipher and one-time pad

The XOR operation doesn’t leak information about the original plaintext (sometimes called “perfectly balanced”). In other words, knowing the result of an XOR operation doesn’t allow us to infer whether the original bit was more likely 0 or 1.”

It also has the property of being its own inverse:

These properties makes it useful in both encryption and decryption.