The KM3NeT Collaboration was formed to build, install and operate the first phase of the KM3NeT Research Infrastructure in the Mediterranean Sea which houses a network of neutrino detectors and ports for Earth and Sea science research. KM3NeT-phase1 is an essential step toward a second phase which foresees the construction of ARCA for high energy neutrino astronomy and ORCA for the determination of the Neutrino Mass Hierarchy. The collaboration includes about 240 people from more than 45 institutes or universities from 13 different countries.