An algebraic expression is a valid combination of numbers, variables, and mathematical operations. For example, in the expression $2x+3,$ the variable $x$ is being multiplied by its coefficient $2,$ and this product is then added to the constant $3.$ Algebraic expressions come in many forms. They can be monomials, like the $2x$ in the binomial above expression. In a polynomial, each monomial separated by a $+$ or $-$ sign is called a term. An entire polynomial, like the above trinomial, is also called an algebraic expression. However, an expression that only contains constants is called a numerical or numeric expression.