The results are presented of the theoretical and experimental studies of ferroelectromagnets--crystals with magnetic and ferroelectric ordering. Considerable attention is paid to reviewing the results of the phenomenological analysis of the influence of the magnetoelectric interaction on the thermodynamic properties of ferroelectromagnets, their reaction to constant and variable electric and magnetic fields, the spectrum of spin waves and ferroelectric oscillations and the methods of exciting them. A table is presented of the expected magnetoelectric effects. The existing experimental studies of magnetoelectric interactions are described and the possible applications of ferroelectromagnets are discussed. A table is given of the known ferroelectromagnetic compounds.