Glider aircraft are a type of unpowered aircraft that rely on aerodynamic lift to stay in the air. They are designed to glide smoothly through the atmosphere, using rising air currents, known as thermals, to gain altitude. Gliders are typically made of lightweight materials, allowing them to achieve long flight durations without the need for an engine. Pilots of glider aircraft often launch from a tow plane or a winch, which pulls them into the sky before they release and begin their flight. Gliding is a popular recreational activity and is also used in competitive sports, where pilots aim to cover the greatest distance or stay aloft the longest.