A propeller is a mechanical device that converts rotational motion into thrust, allowing vehicles like airplanes and boats to move through air or water. It consists of blades that spin around a central hub, creating a difference in pressure that pushes the vehicle forward. The design and angle of the blades can vary, affecting efficiency and speed. Propellers are commonly found in various applications, including aircraft, ships, and drones. They can be powered by engines or motors, and their performance is influenced by factors such as size, shape, and material. Understanding propellers is essential for optimizing the performance of these vehicles.