In terms of an equation, it states that, for any two variables or numbers - a and b,
(a x b) = (b x a)
It could be restated in the following way - for the variables or numbers p,q, and r,
(p x q) = r = (q x p)
Read more at Buzzle: http://www.buzzle.com/articles/commutative-property-of-multiplication.html