The chapter discusses the magnetospheric current system and the formation of field-aligned electric fields in pulsar electrodynamics. It emphasizes the role of the magnetospheric loop current system induced by the pulsar wind activity. The formation of the field-aligned electric field is explored, particularly the reaction of the inner magnetosphere to induced currents. The traditional outer gap, where current-carrying particles are created within the gap, is contrasted with the scenario where external current-carrying particles are added, leading to the movement of the gap inward or outward, and even near the star. The chapter also delves into the constraints on the inner magnetosphere, including the inflexibility of the magnetic field and the dominance of electromagnetic forces. The outer gap is described as a region where particle creation and pair production can occur, contributing to the outflow of energy and the formation of a steady electric field. The chapter concludes by discussing various models of the inner magnetosphere and the potential for future research to better understand the electrodynamics of pulsar magnetospheres.The chapter discusses the magnetospheric current system and the formation of field-aligned electric fields in pulsar electrodynamics. It emphasizes the role of the magnetospheric loop current system induced by the pulsar wind activity. The formation of the field-aligned electric field is explored, particularly the reaction of the inner magnetosphere to induced currents. The traditional outer gap, where current-carrying particles are created within the gap, is contrasted with the scenario where external current-carrying particles are added, leading to the movement of the gap inward or outward, and even near the star. The chapter also delves into the constraints on the inner magnetosphere, including the inflexibility of the magnetic field and the dominance of electromagnetic forces. The outer gap is described as a region where particle creation and pair production can occur, contributing to the outflow of energy and the formation of a steady electric field. The chapter concludes by discussing various models of the inner magnetosphere and the potential for future research to better understand the electrodynamics of pulsar magnetospheres.