The Cosmic Microwave Background: a window on the early universe

Almost 50 years of research on the Cosmic Microwave Background (CMB) have produced a revolution in our understanding of the Universe and of its evolution. These measurements test the deepest issues linking cosmology and fundamental physics, namely inflation, the strange composition of our universe, and the formation of its structures. We review the current status of the measurements and the related experimental methods. We conclude describing a few selected forthcoming CMB experiments, studying the finest details of the CMB (polarization, Gaussianity, spectrum and spectral anisotropy).