Onset of deconfinement and search for the critical point of strongly interacting matter at CERN SPS energies

The study of central collisions of heavy nuclei at CERN SPS energies revealed rapid changes in the energy dependence of hadron production properties in a narrow range around 30A GeV. The results indicate the onset of deconfinement in the early stage of the produced system and motivates the ongoing search for the predicted critical point. NA49 data on event-by-event fluctuations of transverse momentum, multiplicity, particle ratios as well as low mass pion pairs number fluctuations are shown as a function of beam energy and system size. (author)