An inductor is a passive component consisting of two basic parts: a core and a coil. Core material can be ferrite (which is iron) or metal composite. A coil with no core (or “air” as depicted in this slide) is also considered an inductor. Different core materials change the strength of the magnetic field of the inductor. When current passes through the coil, it generates a magnetic field around the coil, which then stores energy. That energy is used as a reserve when there is a sudden change or demand in current.