The proposed Systematic Theory of the Electric Field (STEF) is based on continuum mechanics. The foundation for the theory is laid by the conceptual framework that relies on the totality of derivatives of electric field energy with respect to main arguments (charge, distance, speed). In comparison with the theory of electromagnetism, STEF has made mathematical description simpler, physical essence of phenomena - easier to grasp, and has considerably broadened the explanatory capabilities of science. The study has achieved theoretical justification of all empirical laws that presently form the core of electromagnetic theory, and a number of new results have been obtained that turned out unattainable for the traditional physics of electricity.