The first detection of a gravitational-wave signal emitted by a compact binary coalescence was made by LIGO detectors on September 14, 2015. The event, associated with a binary black hole merger, ushered the era of GW astronomy, offering a new way to probe our Universe. Since then the LIGO-Virgo-KAGRA Collaboration uncovered more than 100 additional GW signals. These are all generated by compact binary coalescence sources, mostly BBHs, with a handful compatible with the presence of at least one neutron star in the binary. In this talk, I will provide an introduction to gravitational waves and their sources, followed by an overview of the relevant observational results obtained by the LVK collaboration.