Many important examples of C*-algebras are constructed from topological groupoids, which arise naturally in a variety of areas such as dynamics, topology, geometry and group theory. While a satisfactory theory of groupoid C*-algebras has been developed for groupoids which are Hausdorff, mysterious phenomena and new challenges arise in the setting of non-Hausdorff groupoids. This talk is about a new approach to non-Hausdorff groupoids and their algebras based on Timmermann’s construction of Hausdorff covers (joint work with Brix, Gonzales and Hume).