INRIM is a public research centre and is Italy's national metrology institute (NMI). INRIM realises, maintains, and disseminates the national reference standards of the measurement units of the International System (SI). INRIM's research spans many other areas such as materials science, nanoscience, quantum optics, studies on the fundamental constants of physics. Basic and applied research and the development of new measurement technologies and instruments enhance the metrology activity. The Institute supports the National Laboratory Accreditation System by ensuring the quality of measurement standards and procedures and promoting the dissemination of the national standards of the SI measurement units. The Division “Quantum Metrology and Nanotechnology” has a sector devoted to “Time and Frequency”, where the Italian Timescale is generated using atomic clocks, among them four commercial Hydrogen Maser and a Caesium fountain. Now, INRiM operates also optical clock base on neutral Ytterbium . Since decades, INRiM is involved with the development of the GNSS Galileo, and its timing facilities. INRiM compares and disseminates its time and frequency standards with satellite techniques (two way and GNSS systems), fibre links, and offers also an NTP synchronization and certified time over fibre.