In recent years, brushless DC motors and controllers have begun an unparalleled triumph in model construction and in all technical fields. This book is intended to show how a brushless motor works. The basic principle is discussed first, before all the key terms such as kV and rpm/V, operating voltage, load and idle current, torque, turns, electrical and mechanical power, losses, efficiency, etc. are explained. A brushless motor can't work without a brushless controller, it requires a three-phase AC voltage. To increase the speed properly, the controller must have information on the rotor position. This can be done by Hall sensors or directly via the motor windings. All that will be taken into account in the book.