  We review observational evidence for a matter-antimatter asymmetry in the
early universe, which leads to the remnant matter density we observe today. We
also discuss observational bounds on the presence of antimatter in the present
day universe, including the possibility of a large lepton asymmetry in the
cosmic neutrino background. We briefly review the theoretical framework within
which baryogenesis, the dynamical generation of a matter-antimatter asymmetry,
can occur. As an example, we discuss a testable minimal model that
simultaneously explains the baryon asymmetry of the universe, neutrino
oscillations and dark matter.
