expression

Expression is a term used across disciplines to denote forms that convey meaning or compute values. In mathematics, computer science, linguistics, and everyday use, an expression represents a value or an idea expressed through symbols, signs, or gestures.

In mathematics, an expression is a finite combination of symbols that denotes a value. It may include constants, variables, operators, and functions, and it can be simplified or evaluated to produce a result. An expression differs from an equation, which asserts equality, and from an identity, which holds for all allowed values.

In programming, an expression evaluates to a value when its operands are computed. It may involve arithmetic, logical, or function calls. Expressions are distinct from statements, which perform actions, and language rules determine evaluation order and types.

In linguistics and everyday language, expression refers to the conveyance of meaning or emotion. Facial expressions, gestures, and tone communicate attitudes beyond words, while phrases or idioms are expressions in a language that carry cultural meaning.

Expression also appears in the arts and psychology to describe the presentation of emotion or intent, as in expressive style, performance, or expression marks in music, which guide phrasing and dynamics.

See also: equation, identity, syntax, semantics.