A self-contained introduction to general relativity that is based on the homogeneity and isotropy of the local universe. Emphasis is placed on estimations of the densities of matter and vacuum energy, and on investigations of the primordial density fluctuations and the nature of dark matter.The book is aimed at astrophysics students and professional physicists who wish to understand the basics of cosmology and general relativity as well as the observational foundations of the LambdaCDM model of the Universe.§The book provides a self-contained introduction to general relativity that is based on the homogeneity and isotropy of the local universe. The simplicity of this space allows general relativity to be presented in a very elementary manner while laying the foundation for the treatment of more complicated problems.§The new edition presents the most recent observations, including those of CMB anisotropies by WMAP and of Baryon Acoustic Oscillations by SDSS. Future observational and the