Operators are symbols, such as + and −, that join variables and numbers to form expressions. These variables and numbers—the objects in the expression—are called operands. For example, the operands for the + in the following expression are x and y:

Operands can be made of any number of terms. The operands for the exponent operator are a (one term) and x + y (two terms).

Some operators have different meaning depending on their arguments. For example, the determinant operator when applied to a scalar returns the absolute value of the scalar. When this operator is applied to a matrix, it returns the determinant of the matrix.