The chapter reviews inductor theory and describes various integrated inductor options. It also explains why integrated planar spiral inductors are so useful when it comes to integrated RF circuits. Furthermore, the chapter discusses the theory of spiral inductor design, inductor modeling, and how this theory can be used in inductor synthesis. In the central part of the chapter, the authors present a methodology for synthesis of planar spiral inductors, where numerous geometries are searched through in order to fit various initial conditions.