  This is a complete re-write of the mini-review for the Review of Particle
Physics (a.k.a the Partcicle Data Book), which includes an assessment of the
CMB anisotropy results and their interpretation up until the end of 2003. It
forms a compact overview of the field at this time. Sections headings are:
Introduction; Description of CMB Anisotropies; Cosmological Parameters; Physics
of Anisotropies; Current Anisotropy Data; CMB Polarization; Complications;
Constraints on Cosmologies; Particle Physics Constraints; Fundamental Lessons;
and Future Directions.
