  The realisation that the electroweak anomaly can induce significant baryon
number violation at high temperature and that the standard models of particle
physics and cosmology contain all the ingredients needed for baryogenesis has
led to vigourous search for viable models. The conclusions so far are that the
Standard Model of particle physics cannot produce baryon asymmetry of required
magnitude. It has too little $CP$ violation and sphaleronic transitions wipe
out any asymmetry produced if the Higgs is heavier than about 50 GeV, a range
already excluded by accelerator experiments. We review the sphaleron solution,
its connection to the high temperature anomalous rate and then summarise
possibilities where phenomenologically testable extensions of the Standard
Model may yet explain the baryon asymmetry of the Universe.
