  Understanding the disparate mixing patterns between quarks and leptons is one
of the major challenges in particle theory today. I discuss some of the ways to
understand this difference within the seesaw framework using new symmetries of
quarks and leptons. After a brief introduction to the various types of seesaw
formulae, proposals for understanding large solar and atmospheric mixings for
the three mass hierarchies i.e. normal, inverted and degenerate, are presented
and their implications discussed.
