  The origin of the asymmetry between matter and anti-matter of the Universe
has been one of the great challenges in particle physics and cosmology.
Leptogenesis as a mechanism for generating the cosmological baryon asymmetry of
the Universe has gained significant interests ever since the advent of the
evidence of non-zero neutrino masses. In these lectures presented at TASI 2006,
I review various realizations of leptogenesis and allude to recent developments
in this subject.
