What is Composition of functions: The composition of two functions f(x) and g(x) is the function h(x) = f(g(x)), where h(x) is a function such that for any x in the domain of g(x), h(x) = f(g(x)).
For example, if f(x) = x^2 and g(x) = x + 1, then h(x) = f(g(x)) = (x + 1)^2 is the composition of f(x) and g(x).