Book excerpt: The physics of neutrinos has acquired a rapidly increasing role within the realm of particle physics. Recognized as an elusive particle since the prediction of its existence by Pauli and its incorporation into particle theory by Fermi in the early thirties, the neutrino was first observed some twenty years later by Reines and Cowan. Experiments carried out by Lederman, Schwartz, Steinberger et al. first revealed the existence of several species of neutrinos. By now, neutrino physics has matured to the point where detailed properties of neutrinos and their mixing can be studied by a number of experiments carried out in various high energy laboratories. Such experiments are relevant not only from viewpoint of understanding the properties of elementary particles, but also the early history of the Universe.This volume discusses the most recent experimental and theoretical results in that exciting area of particle physics.