The notation f(g(x)) and g(f(x)) may be easier to understand than using the composition operator. For f(g(x)), think of wrapping a package. The gift is put into the box (the gift is g(x), the box is f...The notation f(g(x)) and g(f(x)) may be easier to understand than using the composition operator. For f(g(x)), think of wrapping a package. The gift is put into the box (the gift is g(x), the box is f(x)) and the wrapped present, f(x), contains the gift g(x).