  The field of research on magnetic van der Waals compounds -- a special
subclass of quasi-two-dimensional materials -- is currently rapidly expanding
due to the relevance of these compounds to fundamental research where they
serve as a playground for the investigation of different models of quantum
magnetism and also in view of their unique magneto-electronic and
magneto-optical properties pertinent to novel technological applications. The
Electron Spin Resonance (ESR) spectroscopy plays an important role in the
exploration of the rich magnetic behavior of van der Waals compounds due to its
high sensitivity to magnetic anisotropies and unprecedentedly high energy
resolution that altogether enable one to obtain thorough insights into the
details of the spin structure in the magnetically ordered state and the
low-energy spin dynamics in the ordered and paramagnetic phases. This article
provides an overview of the recent achievements in this field made by the ESR
spectroscopic techniques encompassing representatives of antiferro- and
ferromagnetic van der Waals compounds of different crystal structures and
chemical composition as well as of a special category of these materials termed
magnetic topological insulators.
