Foggin up...easy fix I hear?

What up. My car windows fog up like a biatch when I am drive in cold and rainy weather. I have the defroster on, front and back and the back works well but the side windows and the front is pretty crappy. Just enough so that I can see but it is still not enough for me. I know there is some sort of spray is it? That you can buy that fixes this problem. Anyone have a brand name?