A review of our present knowledge concerning the solvation of excess electrons e−exc → e−solv produced by photoionization or radiolysis in polar media has been attempted. Various properties of the solvated electron (proposed solvation mechanisms, structure, physicochemical characteristics) are considered. In spite of some similarities, e−solv does not seem to be a good prototype for solvated halide anions. The behavior of e−exc in heterogeneous model systems, such as micellar solutions and molecular clusters, is described and correlated with that observed in homogeneous media. Key words: excess electrons, homogeneous and heterogeneous polar media, photoionization, radiolysis, solvation, charge transfer to solvent, properties of the solvated electron, micellar solutions, molecular clusters, comparison with the solvation of anions.