In most languages, statements contrast with expressions in that statements do not return results and are executed solely for their side effects, while expressions always return a result and often do not have side effects at all. Among imperative programming languages, Algol 68 is one of the few in which a statement can return a result. In languages that mix imperative and functional styles, such as the Lisp family, the distinction between expressions and statements is not made: even expressions executed in sequential contexts solely for their side effects and whose return values are not used are considered 'expressions'. In purely functional programming, there are no statements; everything is an expression.

This distinction is frequently observed in wording: a statement is executed, while an expression is evaluated. This is found in the exec and eval functions found in some languages: in Python both are found, with exec applied to statements and eval applied to expressions.

Из-за путаницы с терминологией словом «оператор» в программировании нередко обозначают операцию (англ. operator), см. Операция (программирование).