Cosmology courses are very popular with physics undergraduates. Unfortunately, not many of these students have the rigorous mathematical training that is needed to read most textbooks. This textbook is different: introductory cosmology specifically for final-year physicists. It is a concise treatment which can be mastered in a short lecture course. The authors first introduce the concepts of the Standard Big Bang cosmology model. Then they describe the origin and properties of the background radiation. Finally there is an up-to-date account of current experiments and their results.