Cosmic microwave background: probing the universe from z = 6 to 1100

Observations of cosmic microwave background temperature and polarization fluctuations are sensitive to both physical conditions at recombination (z = 1100) and physical process along the line of sight. I will discuss recent results from the Wilkinson Microwave Anisotropy Probe and planned ground and space-based observations. The talk will emphasize the role of CMB observations in determining the initial conditions for the growth of structure and as a probe of the physics of re-ionization.