  Since the discovery of the Cosmic Microwave Background (CMB) in 1965,
characterization of the CMB anisotropy angular power spectrum has become
somewhat of a holy grail for experimental cosmology. Because CMB anisotropy
measurements are difficult, the full potential of the CMB is only now being
realized. Improvements in experimental techniques and detector technology have
yielded an explosion of progress in the past couple of years resulting in the
ability to use measurements of the CMB to place meaningful constraints on
cosmological parameters. In this review, I discuss the theory behind the CMB
but focus primarily on the experiments, reviewing briefly the history of CMB
anisotropy measurements and focusing on the recent experiments that have
revolutionized this field. Results from these modern experiments are reviewed
and the cosmological implications discussed. I conclude with brief comments
about the future of CMB physics.
