At first glance toric varieties do not seem so well adapted to many of the famous questions in birational geometry – they are all birational to each other and the canonical class of a projective toric variety is never nef. On the other hand, polarised toric varieties admit an elegant construction as a torus quotient (up to torsion). Setting this construction in the framework of GIT the choice of ample class now becomes a ‘stability condition’, which may now range over the whole effective cone. This induces a fan structure on this cone, the ‘secondary fan’: passing into and across the walls created by this fan induces certain well-known birational transformations associated to extremal rays, namely flips, divisorial contractions and fibering contractions.