Originally published as part of the renowned Bergmann-Schaefer textbook series on experimental physics, this volume fills an important void by providing a thorough treatment of the basic: atoms, molecules, nuclei, and particles. Written by experimentalists, it forms a unique compendium of our practical knowledge of the basic elements While keeping all of the rigor necessary for a clean treatment, the authors go beyond theory and describe major experimental results that give readers a clear view of the practical side of nature.