This article commences with a description of the principles of induction heating followed by a discussion on the high temperature electrical, magnetic, and thermal properties of steel, which influence the performance of induction heaters. The importance of eddy current distribution in a workpiece is explained, with emphasis on the skin effect. The article discusses typical procedures for induction hardening of steel, namely, austenitizing and quenching to form martensite either on the surface (case hardening) or through the entire section (through hardening). It briefly describes induction heating parameters for surface hardening, through hardening, tempering, and some general heating operations in metalworking.