Cosmic microwave background observations and cosmology

Observations of the Cosmic Microwave Background (CMB) play a pivotal role in the development of modern cosmology. Most of the predictions of the Hot Big Bang model are now experimentally confirmed, and the parameters of the model have recently been constrained to good accuracy. The so-called "Concordance cosmology", derived from observations of the CMB spectrum and anisotropy, from measurements of the large-scale distribution of galaxies, of the expansion of the Universe and of the abundance of light elements, requires significant contributions from dark matter (Omegam similar to 0.3) and dark energy (Omega(Lambda) similar to 0.65). Also, an initial inflation phase is required for the model to be self consistent. Here we focus on CMB anisotropy and CMB polarization observations and on their role in constraining the model.