It is an observational fact that the universe contains more baryons than
antibaryons. This is true of our immediate environment in particular
but,
as we
shall see, also on scales on the order of the Hubble length. The
domination of baryons over antibaryons raises a
number of questions. The first is: how large is the baryon density of
the
universe? For that, see Sec. 2. Could it be that this excess
is only local, that the antimatter is hiding somewhere?
Sec. 3 dispatches that question. Is there a ``microphysical''
mechanism for generating a baryon excess from symmetric initial
conditions (a so-called baryogenesis mechanism)? We survey the
possibilities in Sec. 4. Finally, in
Sec. 5 we look at possible experimental confirmation for the
proposed microphysical mechanisms.