What processes fixed the designs etched on the cosmic background radiation (CBR)? And what can they tell us about the early Universe, and the origin and evolution of cosmic structure? This review covers all aspects of three decades of study of this ghostly remnant of the hot Big Bang origin of the Universe, and examines the consequences for astrophysics, cosmology and theories of the evolution of large-scale cosmic structure. The observational techniques used to measure the spectrum of CBR, and its angular distribution on the sky, are examined in clear but critical detail: from the work of Penzias and Wilson in 1964, to results from NASA's Cosmic Microwave Background Explorer (COBE) satellite. This review takes these observations and shows how they have shaped our understanding of the early history of the Universe, and of the origin and evolution of the large-scale structures in it. As a reference this book is suitable for researchers, with introductory chapters in cosmology and radio astronomy provided for graduates in physics and astronomy entering into cosmology or CBR research.

"At last, there is a comprehensive book on the cosmic microwave background radiation (CBR). What's more, it's a good one. Bruce Partridge's 3K: The Cosmic Microwave Background Radiation contains everything you need to get a solid foundation in this exciting and rapidly growing field. One of the pioneers, Partridge is still active in wrestling secrets from the CBR. His book summarizes the theoretical framework in which to interpret the measurements and gives a detailed account of the instrumentation and observations. It is clear, informative, and fun to read....Partridge has written a book that will be relevant for years to come." Lyman Page, American Journal of Physics

"After 30 years, the cosmic background radiation remains the most promising probe of the early universe. Over the next ten years, startling claims will emerge from the CBR community. Estimates of the Hubble constant, curvature of the universe, and cosmological constant accurate to a few percent will be made. For both the people making these claims and those attempting to understand their validity, this book will be an essential resource." Scott Dodelson, Science