The study of the nucleon-nucleon interaction has a long history, going back to 1932 (just after the discovery of the neutron by James Chadwick). The force is responsible for binding protons and neutrons into atomic nuclei but, unlike the cases of Coulomb or Newtonian gravitational laws, the form of the fundamental NN strong interaction and its constants are a priori unknown. The subject is nevertheless important because the energy associated with the binding of protons and neutrons to form atomic nuclei is the energy used in nuclear power. The authors of the present volume deliver accounts of current research on various aspects of the forces between two or more nucleons and how they relate to experiments in nuclear physics. General overviews, illustrated by appropriate examples, are given both the theoretical and experimental knowledge of nuclear physics that are prerequisites for the understanding of the strong interaction. Two- and three-nucleon forces are among the topics that are addressed and discussed including, for example, how nuclear forces emerge from low-energy QCD via chiral effective field theory. A comprehensive overview is presented of realistic free nucleon-nucleon interactions and also two-nucleon dynamics in a nuclear medium.