The neutrino is the most fascinating elementary particle due to its elusive nature and outstanding properties that have attracted the interest of generations of physicists since 1930, when it was first postulated by Wolfgang Pauli as a 'desperate remedy' to explain the apparent energy violation in the beta decay. Many fundamental discoveries in particle physics had the neutrino involved in one way or another. To date, neutrino physics is still one of the hottest topics of modern particle physics. Key experiments and significant theoretical developments have contributed in building up what we can call now the Standard Model of Neutrino Physics.The aim of the book is to provide graduate students and young researchers a comprehensive tutorial in modern neutrino physics, specially tailored with emphasis on the educational aspects. It provides an overview of the basics and of recent achievements in the field, from both experimental and theoretical points of view.