This chapter stresses the importance of drilling the basics. It begins with a thorough review of Ohm's Law (voltage equals current multiplied by resistance) and its applications. The next foundational formula explained is the voltage divider rule, followed by Thevenin's theorem, each of which is illustrated with plentiful examples and figures. While still applying these basics formula, the discussion moves to various relationships and interactions among voltage and current, expanding on alternating current (AC) and direct current (DC); capacitors and inductors; low-pass filters, high-pass filters, and active filters; and magnetic fields and electric fields. The chapter concludes with a brief discussion of control theory in order to illuminate the concept of systems, step input, feedback, and open-loop gain versus closed-loop gain.