Let G be a reductive group acting on a quasi-projective variety X. The construction of the geometric invariant theory (GIT) quotient of X by G depends on the choice of an ample line bundle on X with a compatible action of G. Changing this line bundle often results in a birational map of GIT quotients (a flip), which aids in understanding the birational geometry of these spaces. I’ll give an introduction to these ideas, focusing on the case where G is a torus and X is affine space, which corresponds to the case of toric varieties.