An expression in mathematics or computer programming consisting of two other expressions multiplied together. In mathematics, multiplication is usually represented by juxtaposition, e.g. "x y", whereas in programming, "*" is used as an infix operator, e.g. "salary * tax_rate.
In the most common type of product, each operand is a number (integer, real number, fraction or imaginary number) but the term extends naturally to cover more complex operations like multiplying a string by an integer (e.g., in Perl, "foo" x 2) or multiplying vectors and matrices or more than two operands.
In type systems, a tuple is sometimes known as a "product type".