I describe the evidence for the big bang, including the various cosmological parameters. There is general concordance on their values, although the uncertainties remain large enough to justify the ensuing debate. Structure formation is reviewed, and here there is consensus on the hierarchical nature of the sequence of formation. The cosmic microwave background anisotropies provide a glimpse of the initial conditions that seeded structure, and the evolution of clouds of dark matter is an inevitable consequence. There are two outstanding mysteries: the very beginning, where a theory of quantum gravity is eagerly awaited, and the detailed nature of galaxy formation, where observations are well ahead of theory.