I. Preliminaries -- 1. Introduction and Overview -- 2. Special relativity: the basics -- II. Relativity - Metric Description of Spacetime -- 3. Special relativity: the geometric formulation -- 4. Principle of equivalence -- 5. Metric description of a curved space -- 6. GR as a geometric theory of gravity - I -- 7. Spherically symmetric spacetime - GR tests -- 8. Black holes -- III. Cosmology -- 9. Homogeneous and isotropic universe -- 10. Expanding universe and thermal relics -- 11. Inflation and the accelerating universe -- IV. Relativity - Full Tensor Formulation -- 12. Tensors in special relativity -- 13. Tensors in general relativity -- 14. GR as a geometric theory of gravity - II -- 15. Linearized theory and gravitational waves -- Physical constants