The main experimental works devoted to the study of spin properties of two-dimensional electronic systems by means of electrically detectable electron spin resonance are discussed. The key aspects of spin resonance — detection mechanism, anisotropy of spin splitting, influence of hyperfine and spin-orbit interaction on the physics of spin resonance — are considered. Special attention is paid to systems with strong electron-electron interaction formed in various AlAs/AlGaAs and ZnO/MgZnO semiconductor heterostructures. It is in such material systems that a whole series of unique physical phenomena related to spin have been observed. The prospects of electron spin resonance in two-dimensional systems are discussed.