  The study of cosmic microwave background (CMB) polarization is still in a
pioneering stage, but promises to bring a huge advancement in cosmology in the
near future, just as high-accuracy observations of the anisotropies in the
total intensity of the CMB revolutionized our understanding of the universe in
the past few years. In this contribution, we outline the scientific case for
observing CMB polarization, and review the current observational status and
future experimental prospects in the field.
