This chapter transitions from electrostatics to electrodynamics, focusing on the flow of electric charge as electric currents. It begins with a microscopic description of conductivity using Drude’s model, explaining how free electrons in a conductor acquire a drift velocity under an applied electric field, leading to a steady current. The concepts of carrier lifetime and mobility are introduced to characterize this microscopic behavior. The chapter then derives Ohm’s law in both its local and macroscopic forms, establishing the fundamental relationship between current density, electric field, and the material conductivity (or resistivity). It explores the implications of time-varying electric fields on conductivity and discusses the phenomenon of charge neutrality in conductors, introducing the concept of dielectric relaxation time. A brief overview of conductors, semiconductors, and superconductors highlights their distinct electrical properties, particularly their temperature dependence. The latter part of the chapter examines in detail DC circuit elements and electrical networks. It defines bipoles (two-terminal devices) and introduces the passive sign convention for consistent circuit analysis. The concept of electrical power in circuit components, including the Joule effect (power dissipated as heat in resistors), is thoroughly discussed. Various types of bipoles, such as resistors, diodes (including PN junction, LED, Zener, and tunnel diodes), and ideal sources (voltage and current), are characterized by their current-voltage (I-V) characteristics. Finally, the chapter lays out the foundational rules for analyzing complex electrical networks: Kirchhoff’s Current Law (KCL), based on charge conservation at nodes, and Kirchhoff’s Voltage Law (KVL), derived from the conservative nature of the electric field in steady states. It introduces powerful circuit simplification theorems, including the Superposition theorem for linear circuits with multiple sources, and Thévenin’s and Norton’s theorems for reducing complex two-terminal networks to simpler equivalent circuits. The chapter concludes with a discussion of voltmeters and ammeters and their operating principles.