Neutrino physics

The discovery of neutrino oscillations just over 20 years ago has opened a new page in particle physics. It implies that neutrinos have masses and mix and, consequently, that the Standard Model of particle physics is incomplete. The key question we need to answer is: what is the origin of neutrino masses and of leptonic mixing? An impressive effort has being able to paint a precise picture of neutrino mixing. The first hints of CP violation have been reported and hunts for the nature of neutrinos are ongoing. This information guides us in extending the Standard Model to a full theory, advocating new particles and interactions. We will present a concise discussion of these issues, focusing mainly on the theoretical and phenomenological aspects and we will briefly discuss the role of neutrinos in the early Universe and in astrophysical objects.