Boolean algebra

Set of algebraic rules, named after English mathematician George Boole, in which TRUE and FALSE are equated to 0 and 1. Boolean algebra includes a series of operators (AND, OR, NOT, NAND (NOT AND), NOR, and XOR (exclusive OR)), which can be used to manipulate TRUE and FALSE values (see truth table). It is the basis of computer logic because the truth values can be directly associated with bits.

These rules are used in searching databases either locally or across the Internet via services like Google to limit the number of hits to those which most closely match a user's requirements. A search instruction such as ‘tennis NOT table’ would retrieve articles about tennis and reject those about ping-pong.