In 1904 Poincare asked the following question (reformulated in modern language): "If $M$ is a closed 3-manifold with trivial fundamental group, then is $M$ diffeomorphic to $S^3$?" The Poincare conjecture is that the answer to this question is 'Yes'. In the 1980's Thurston formulated a more general conjecture, called Thurston's Geometrization Conjecture for 3-manifolds, which includes the Poincare conjecture as a special case. In this talk we will state Thurston's conjecture and give a short proof of the Poincare conjecture as a corollary.