The topics of nuclear physics, particle physics and cosmology are closely connected. As the first volume of a two-volume set, this book covers nuclear physics and can be treated as a complete course on the subject. The book is divided into a set of eight modules or chapters and covers the majority of topics referred to in undergraduate and postgraduate courses on nuclear physics, such as radioactivity, nuclear models, nuclear reaction, nuclear fission and fusion, deuteron problem and scattering. This course text follows a simple style, with a lucid approach and step-by-step explanations. Every effort has been made to describe things in a manner that is understandable and care has been taken to provide illustrations whenever applicable.