In algebra, a multilinear polynomial is a polynomial that is linear in each of its variables. In other words, no variable occurs to a power of 2 or higher; or alternatively, each monomial is a constant times a product of distinct variables. They are important in the study of polynomial identity testing, because if a multilinear polynomial is zero on a set of vectors that span the space, it will be zero everywhere. The degree of a multilinear polynomial is the maximum number of distinct variables occurring in any monomial.