The ALICE apparatus includes an Inner Tracking System for high-precision vertexing and tracking at midrapidity. Thanks to this detector, remarkable results were obtained with Run 2 data in all collision systems studied at the LHC.
In this contribution, the role of the ITS in the event, track and secondary vertex reconstruction is highlighted, and the comparison of the resolution on the track impact parameter to the collision point in data and Monte Carlo simulations is reported. Finally, some of the main physics results obtained in pp and Pb-Pb collisions relying on the excellent ALICE vertexing and tracking capabilities are presented.