Boolean expression

A type of expression that reduces to a true or false (logical) condition. A Boolean expression contains logical expressions (e.g., DEPTH > 100) and Boolean operators. A Boolean operator is a keyword that specifies how to combine simple logical expressions into complex expressions. Boolean operators negate a predicate (NOT), specify a combination of predicates (AND), or specify a list of alternative predicates (OR). For example, DEPTH > 100 AND DIAMETER > 20. See also logical selection.

An expression whose result is of type boolean, i.e. gives a value of either true or false. Operators such as && and || take boolean operands and produce a boolean result. The relational operators take operands different types and produce boolean results.