The expanding Universe and the Big Bang -- Relativistic theory -- The propagation of light and measurements of distance, luminosity, and mass -- Evidence for Dark Matter and the ACDM model -- The Early Universe and its thermal history -- Big Bang Nucleosynthesis and Recombination -- The Cosmic Microwave Background Radiation (CMBR) anisotropy -- Problems to be solved by inflation and how they are solved in inflationary models -- Slow-roll inflation -- Reheating and baryogenesis -- Fluctuations in inflation and matching with experimental data -- Extra dimensions and Kaluza-Klein -- Electromagnetism and gravity in various dimensions. Consistent truncation -- N = 1 supergravity in 4 dimensions -- KK compactification of supergravity models -- The relativistic point particle -- Relativistic strings -- Light-cone gauge strings and quantization -- D-branes and gauge fields -- Electromagnetic fields on D-branes and N = 4 SYM. T-duality of closed strings -- T-duality of open strings. M-theory and the duality web -- String theory and particle physics -- Holography and the AdS/CFT correspondence -- Problems of string inflation -- Problems of the supergravity approximation to string inflation -- Brane- (antibrane) inflation -- Braneworld cosmology and the Israel junction conditions -- The KKLT scenario for de Sitter backgrounds in string theory -- The KKLMMT scenario for inflation and generalizations -- The ekpyrotic scenario -- The cyclic and new ekpyrotic scenarios -- String gas cosmology: basics and Brandenberger-Vafa scenario -- String gas and brane gas developments -- Chameleon scalars and string theory -- Axion inflation and axion monodromy from string theory -- Fuzzy dark matter from string theory -- Holographic cosmology.