In the last fifteen years, various areas of high energy physics, astrophysics and theoretical physics have converged on the study of cosmology so that any graduate student in these disciplines today needs a reasonably self-contained introduction to the Cosmic Microwave Background (CMB). This book presents the essential theoretical tools necessary to acquire a modern working knowledge of CMB physics. The style of the book, falling somewhere between a monograph and a set of lecture notes, is pedagogical and the author uses the typical approach of theoretical physics to explain the main problems in detail, touching on the main assumptions and derivations of a fascinating subject.Contents:Why CMB Physics?From CMB to the Standard Cosmological ModelProblems with the SCMSCM and BeyondEssentials of Inflationary DynamicsInhomogeneities in FRW ModelsThe First Lap in CMB AnisotropiesImproved Fluid Description of Pre-Decoupling PhysicsKinetic HierarchiesEarly Initial Conditions?Surfing on the GaugesInteracting FluidsSpectator FieldsAppendices:The Concept of Distance in CosmologyKinetic Description of Hot PlasmasScalar Modes of the GeometryMetric Fluctuations: Gauge Independent TreatmentReadership: PhD students and researchers in physics, astrophysics and astronomy.