  PHOBOS is one of four experiments studying Au-Au collisions at RHIC. During
the first running period RHIC provided Au+Au collisions at $\sqrt{s_{_{NN}}}$ =
56 GeV and 130 GeV. The data collected during this period allowed us to study
the energy and centrality dependence of particle production, the anisotropy of
the final state azimuthal distribution and particle ratios at mid-rapidity.
