Polynomial functions follow a specific formula where terms are in descending order by the exponent of x. All polynomial functions have zeros, which are the x-intercepts with opposite signs. Examples are provided of polynomial functions in standard form with positive, integer exponents like f(x) = 6x^4 - 3x^2 + 2x - 5. Non-polynomial functions do not follow these rules, such as having negative exponents or non-descending terms. Important properties of polynomial functions include the degree, leading coefficient, factored and standard forms.