The new inner tracking system for the ALICE upgrade at the LHC

ALICE, the CERN LHC experiment devoted to the study of the QGP (Quark–Gluon Plasma) properties, will undergo a comprehensive upgrade during the second long shutdown of the LHC (in 2019–2020) to enhance the capability for high precision measurements of rare processes at low transverse momenta ($P_{T}$). One of the key elements of the upgrade strategy is the novel, high-resolution, ultra-light Inner Tracking System (ITS) consisting of seven concentric layers of Monolithic Active Pixel Sensors (MAPS) covering a total active area of 10 m$^{2}$ segmented in 12.5 Gpixels. This paper presents an overview of the detector components, the most relevant characterisation results and the status of the detector construction.