  The Silicon Pixel Detector (SPD) constitutes the two innermost layers of the
Inner Tracking System of the ALICE experiment and it is the closest detector to
the interaction point. As a vertex detector, it has the unique feature of
generating a trigger signal that contributes to the L0 trigger of the ALICE
experiment. The SPD started collecting data since the very first pp collisions
at LHC in 2009 and since then it has taken part in all pp, Pb-Pb and p-Pb data
taking campaigns. This contribution will present the main features of the SPD,
the detector performance and the operational experience, including calibration
and optimization activities from Run 1 to Run 2.
