expression

An expression is a symbol or of symbols used to denote a quantity or value. Expressions consist of constants, variables, operations, operators, functions, and parentheses.

Note 1. If an expression one or more operations to be performed in a certain http://planetmath.org/OrderOfOperationsorder, the expression may be named after the last (http://planetmath.org/Iei.e. outermost) operation. For example, the expression $a^2-5\sqrt{a}+{\displaystyle \frac{2}{3a}}$ is a sum expression.

Note 2. An equation is a denoted equality of two expressions.