Solar sails are a form of spacecraft propulsion that uses sunlight for movement. They consist of large, reflective sails that capture photons from the sun. As these photons strike the sail, they transfer momentum, pushing the spacecraft forward. This method allows for continuous acceleration without the need for fuel, making it an efficient way to travel in space. Solar sails can be used for various missions, including exploring distant planets and asteroids. They are often compared to traditional sails used in sailing ships, which harness wind for propulsion. Notable projects, like IKAROS and LightSail, have demonstrated the potential of this innovative technology.