This book provides an extensive survey of all the physics necessary to understand the current developments in the field of fundamental cosmology, as well as an overview of the observational data and methods. It will help students to get into research by providing definitions and main techniques and ideas discussed today. The book is divided into three parts. Part 1 summarises the fundamentals in theoretical physics needed in cosmology (general relativity, field theory, particle physics). Part 2 describes the standard model of cosmology and includes cosmological solutions of Einstein equations, the hot big bang model, cosmological perturbation theory, cosmic microwave background anisotropies, lensing and evidence for dark matter, and inflation. Part 3 describes extensions of this model and opens up current research in the field: scalar-tensor theories, supersymmetry, the cosmological constant problem and acceleration of the universe, topology of the universe, grand unification and baryogenesis, topological defects and phase transitions, string inspired cosmology including branes and the latest developments. The book provides details of all derivations and leads the student up to the level of research articles.