  With the discovery of both binary black hole mergers and a binary neutron
star merger the field of Gravitational Wave Astrophysics has really begun. The
current advanced LIGO and Virgo detectors are laser interferometers that will
improve their sensitivity in the coming years. In the long run, new detectors
such as LISA and the Einstein Telescope will have sensitivities that allow the
detection of many thousands of sources and ET can observe essentially the whole
observable Universe, for heavy black holes. All these measurements will provide
new answers to open questions in binary evolution, related to mass transfer,
out-of-equilibrium stars and the role of metallicity. In addition, the data
will give new constraints on uncertainties in the evolution of (massive) stars,
such as stellar winds, the role of rotation and the final collapse to a neutron
star or black hole. For black hole binaries, the number of detections is
rapidly approaching 10 and the first proper statistical studies of the
population can be done soon. In the long run, the thousands of detections by ET
will enable us to probe their population in great detail over the history of
the Universe. For neutron stars, the first question is whether the first
detection GW170817 is a typical source or not. In any case, it has
spectacularly shown the promise of complementary electro-magnetic follow-up.
For white dwarfs we have to wait for LISA (around 2034) but new detections by
e.g. Gaia and LSST will prepare for the astrophysical exploitation of the LISA
