On Observing the Cosmic Microwave Background

The cosmic microwave background (CMB) comprises the oldest photons in the universe and is arguably our most direct cosmological observable. All precise and accurate measurements of its attributes serve to distinguish between cosmological models. Detector technology and observing techniques have advanced to the point where fluctuations in the CMB of order a few microkelvin are measured almost routinely. In these lecture notes, we review recent measurements of both the absolute temperature and the anisotropy of the CMB and discuss the relation between the data and the general theoretical framework. Future directions are indicated and the upcoming satellite experiments are discussed.