The biennal International Symposium on Hysteresis Modeling and Micromagnetics (HMM) is an interdisciplinary forum for discussion of the most recent advancements in the fields of hysteresis modeling and micromagnetics. It aims to bring together scientists with various backgrounds (e.g., mathematicians, physicists, engineers, and materials scientists) to exchange ideas and to present new approaches and results. The 13th edition of HMM will take place from May 31 to June 2, 2021 at TU Wien (Vienna, Austria).