The origin of the asymmetry between matter and anti-matter of the Universe is one of the biggest  unsolved problems 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 this lecture,  I pedagogically review on the mechanism of leptogenesis and allude to recent developments in this subject.