  The detections of gravitational waves (GW) by LIGO/Virgo collaborations
provide various possibilities to physics and astronomy. We are quite sure that
GW observations will develop a lot both in precision and in number owing to the
continuous works for the improvement of detectors, including the expectation to
the newly joined detector, KAGRA, and the planned detector, LIGO-India. In this
occasion, we review the fundamental outcomes and prospects of gravitational
wave physics and astronomy. We survey the development focusing on
representative sources of gravitational waves: binary black holes, binary
neutron stars, and supernovae. We also summarize the role of gravitational wave
observations as a probe of new physics.
