The birth of the gravitational-wave astronomy

Last years marked the beginning of a new era of observations of the Universe. Gravitational waves were detected from a binary black-hole merger by the Advanced LIGO detectors. Simultaneously, LISA Pathfinder demonstrated the technology for gravitational-wave observation in space beyond its planned requirements. Many gravitational observations and discoveries are expected in the next years with the Advanced LIGO and Virgo detectors, with strong impact on various astrophysical fields, from the physics governing compact object formation and evolution to the physics of the emission process and to nuclear astrophysics. I summarize here some historical milestones that led to the first detection and report the perspectives of the field. I also discuss the importance of the so-called multimessenger astronomy in which gravitational-wave sources will be observed in all bands of the electromagnetic spectrum with ground and space observatories and with neutrino telescopes.