Baryogenesis from the weak scale to the grand unification scale

The standard model of elementary particle physics, once augmented with Sakharov's conditions, offers several scenarios to explain today's matter-antimatter asymmetry. This survey evaluates the paths to baryogenesis. Of special interest is that time-reversal violation in neutrino physics, together with large mixings, seems poised to produce the observed asymmetry via leptogenesis. This review occurs at a time when several experiments are on the threshold of a precise measurement of time violation in lepton mixing.