This volume in the renowned Abel Symposia series contains the peer-reviewed proceedings of the Abel Symposium 2023 on Partial Differential Equations: Waves, Nonlinearities and Nonlocalities, held at Bårdshaug Mansion in Orkanger outside Trondheim, Norway, June 13–16, 2023. Research in nonlinear partial differential equations has been undergoing an intense development, with new phenomena modelled by increasingly complicated systems integrating nonlocal effects, and with the solution of previously unsolved problems, such as the Onsager conjecture. Comprising fifteen articles written by leading researchers, covering a wide range of topics, this book takes readers to the forefront of a highly active subject.