The third observing run of LIGO and Virgo, O3, has shown the greatest performance of the detectors to date. We now count around 90 gravitational-wave transient events. The sharp increase in the number of detections was made possible by significant improvements to the instruments with respect to previous observation periods. During (and after) these runs, many searches are carried out to study compact binary coalescences (CBCs), the astrophysical source populations, or even gravitational waves from exotic objects in the Universe. The goal of these analyses is to answer questions such as the rate of mergers taking place in the Universe, the formation channels of compact objects, or the properties of other gravitational wave sources. Among the 35 compact binary mergers detected during the second part of O3, the first gravitational waves from neutron-star-black-hole mergers have been observed. These represent the first confident observations to date of NSBH binaries via any observational means.
The presentation will focus on the main results of O3, especially its second half, and will describe the various tests of general relativity, the detection of the neutron-star-black-hole mergers, and the inferred properties of the astrophysical source population. I will also discuss searches for gravitational waves produced from sources that are not compact binary coalescences.