A rotor ship, also known as a Flettner ship, is a type of vessel that uses rotating cylinders or sails to harness the power of wind to propel itself through the water. The term "rotor ship" is often used interchangeably with "Flettner ship", named after the German scientist who first developed this technology in the 1920s. Additionally, the rotor ship can also be referred to as a "spin sail ship", "cyclorotor ship", or "rotary sail ship". Despite being initially overshadowed by more conventional propulsion systems, the rotor ship has seen a resurgence in popularity due to its eco-friendly and fuel-efficient nature.