The fundamental idea of this introductory textbook is to provide a unified presentation of nuclear and particle physics from an experimental perspective. The reduction of the complex structure of atomic nuclei and nucleons to a few basic building blocks and interactions is the first message of this book. The second part, which describes the structure of nucleons and nuclei from these building blocks, makes it clear that the complexity arising from many-body interactions increasingly governs the laws of composite systems. The book addresses nuclear matter at high temperatures and the role of nuclear and particle physics in astrophysical processes. The latest developments in neutrino physics are presented. The new edition includes new chapters on weak interactions and baryons. The book is written in a concise and clear style.