  The properties of the cosmic microwave background radiation provide unique
constraints on cosmological models, i.e. on the content, history, and evolution
of the Universe. I discuss the latest measurements of the spectral and spatial
properties of the cosmic microwave background radiation. Recent measurements
from NASA's Cosmic Background Explorer (COBE) satellite, and from balloon-borne
and ground-based platforms, are summarized and their cosmological implications
are discussed.
