A unified presentation of nuclear and particle physics from an experimental point of view. The first part of the book is devoted to disentangling the substructure of matter, showing that experiments designed to uncover the substructures of nuclei and nucleons have a similar conceptual basis. This leads to the present picture of all matter being built out of a small number of elementary building blocks and a small number of fundamental interactions. The second part then goes on to show how these elementary particles may be combined to build hadrons and nuclei. This introductory textbook is based on lectures held at the University of Heidelberg and, with its numerous exercises with worked answers, is ideally suited for undergraduate courses.