A polynomial is an algebraic expression consisting of variables, constants, and exponents combined using mathematical operations such as addition, subtraction, multiplication, and division. Polynomials can have one or more variables and terms take the form of axn, where a is the coefficient and n is a non-negative integer exponent. The degree of a polynomial is the highest exponent present in its terms. Examples of polynomials include 2a + 5b, 3xy + 5x + 1, and 3y4 + 2y3 + 7y2 - 9y + 3/5.