This article provides basic knowledge about inductance coil, including its composition, classification, and main characteristic parameters. The article also explains the inductive reactance, quality factor, and distributed capacitance of the coil. The classification of the inductance forms includes fixed inductor, variable inductance, air core coil, ferrite coil, iron core coil, copper core coil, antenna coil, oscillator coil, choke coil, wave trap coil, and deflecting coil. The main characteristic parameters of the inductor coil are inductance L, inductive reactance XL, quality factor Q, and distributed capacitance.