NA61/SHINE at the CERN SPS is a fixed-target experiment pursuing a rich physics program including measurements for heavy ion, neutrino and cosmic ray physics. The main goal of the ion program is to explore the most interesting T;mu _B region of the phase diagram of strongly interacting matter. We plan to study the properties of the onset of deconfinement and to search for the signatures of the critical point. The search is performed by varying collision energy (13A- 158A GeV/c) and system size (p+p, Be+Be, Ar+Ca, Xe+La). Thanks to its large acceptance and excellent particle identification capability NA61/SHINE is well suited for performing high-precision particle production measurements as well as for studying event-by-event fluctuations in p+p, p+nucleus and nucleus+nucleus collisions. Preliminary results on p+p interactions at 20, 31, 40, 80 and 158 GeV/c are presented. They include inclusive spectra of pi+, pi-, K- and protons as a function of transverse momentum/mass and rapidity as well as event-by-event fluctuations of transverse momentum, azimuthal angle and chemical composition. The new NA61 measurements are compared with the corresponding results of NA49 on central Pb+Pb collisions and with predictions of Monte Carlo models. Finally, the future plans of NA61/SHINE are summarised.