Typically an outrunner motor is a Permanent Magnet Synchronous Motor (PMSM) torque motor. Therefore, the motor consists of a stator with coils and a rotor with permanent magnets. With conventional motors, the magnets are attached to a shaft that rotates on the inside of the stator coils. This is called an inrunner motor. With an outrunner motor the magnets are attached to a ring or sleeve on the outside of the stator coils. As a result, the motor has a rotating ring or sleeve, instead of a rotating shaft. Read more and watch the video
