Geometric transitions are topology changing transitions that connect different parts of the Calabi-Yau moduli space, including connecting Kahler and non-Kahler Calabi-Yau metrics. Reid's fantasy predicts that all simply connected Calabi-Yau manifolds can be joined by a sequence of geometric transitions. I will discuss the geometry of geometric transitions, with a specific emphasis on the metric point of view and the equations of motion for the heterotic string.