  We review the application of non-Abelian discrete groups to Tri-Bimaximal
(TB) neutrino mixing, which is supported by experiment as a possible good first
approximation to the data. After summarizing the motivation and the formalism,
we discuss specific models, mainly those based on A4 but also on other finite
groups, and their phenomenological implications, including the extension to
quarks. The recent measurements of \theta_13 favour versions of these models
where a suitable mechanism leads to corrections to \theta_13 that can naturally
be larger than those to \theta_12 and \theta_23. The virtues and the problems
of TB mixing models are discussed, also in connection with lepton flavour
violating processes, and the different approaches are compared.
