This year marks the centenary of two pivotal breakthroughs in physics: the discovery of the Schwarzschild solution, describing a non-rotating black hole, and Einstein's prediction of gravitational waves (GWs). The GW150914 event is the first direct detection of GWs, most likely the first observation of black-hole binaries, and certainly a fitting celebration. Gravitational waves offer a unique glimpse into the unseen universe in different ways, and allow us to test the basic tenets of
General Relativity, some of which have been taken for granted without observations: are gravitons massless? Are black holes the simplest possible macroscopic objects? do event horizons and black holes really exist, or is their formation halted by some as-yet unknown mechanism? In these lectures, we will describe the anatomy of a GW event, with particular emphasis on how to compute gravitational-waves from black hole systems and what kind of information such waves carry.
