The Philosophy and Physics of Duality discusses what dualities are and the philosophical questions that they raise. This book also examines the main examples of duality-from quantum mechanics and electrodynamics to statistical mechanics, quantum field theory, and string theory. Part I conceptualizes dualities and discusses their main roles and themes, including how they are related to familiar notions like symmetry and interpretation. It then goes through the main simple examples of dualities: position-momentum, wave-particle, electric-magnetic, and Kramers-Wannier dualities. Part II discusses advanced examples and their inter-relations: particle-soliton dualities, electric-magnetic dualities in quantum field theories, dualities in string theory, and gauge-gravity duality. Part III offers an in-depth exploration of the general philosophical issues onto which dualities bear: theoretical equivalence, scientific realism and the under-determination of theories by data, theory succession and the M-theory programme, explanation, and scientific understanding. Finally, Sebastian De Haro and Jeremy Butterfield propose a view of scientific theories in this book-they call their account the geometric view of theories. This is an open access title available under the terms of a CC BY-NC-ND 4.0 International licence. It is free to read on the Oxford Academic platform and offered as a free PDF download from OUP and selected open access locations.