Anisotropy and polarization of the microwave background radiation, and the reionization of the universe

We describe the basics of the cosmic microwave background radiation (CMB), and the physics of its anisotropy and polarization. CMB observations have provided us abundant information about the evolution of the universe, including the big bang cosmological model predictions. The most recent observational results of CMB are presented, with emphasis on the polarization detected by Wilkinson Microwave Anisotropy Probe and its implications for the reionization history of the universe.