The objective of this paper is to provide an understanding of the electrical circuit for induction hardening. This includes the power supply, workstation, and inductor. Step by step procedures are provided using a commercial power supply and workstation as an example. The paper addresses questions such as: What is an inductor? How does the inductor connect to a scanner? How is quenching performed in induction? What is load tuning? How do I load tune an induction circuit? How does the induction power supply work? How do I verify induction hardening results? This paper also provides a brief history of induction hardening and discusses how the development of the technology impacts induction hardening today.