Preface - Proceedings of the International School of Physics "Enrico Fermi" - Course 206

The monograph contains the proceedings of the Enrico Fermi Summer School on “New Frontiers for Metrology: from biology and chemistry to quantum and data science”. It was held in Varenna from 4th July to 13th July, 2019 and was organised by the Italian Physical Society (SIF), the Bureau Internationals des Poids et Mesures (BIPM), and the Italian Istituto Nazionale di Ricerca Metrologica (INRIM). The 2019 school was the 7th to have been held in the Enrico Fermi series that has been devoted to metrology. It followed the 26th meeting of the CGPM which adopted new definitions for the base units of the SI and was a milestone in the history of measurement. The programme for the 2019 school also looked to some of the new practical challenges for measurement science. These included the application of metrological principles to the management and interpretation of very large sets of scientific data and the application of metrology to biology