A glider is a heavier-than-air aircraft that usually has no engine. To fly, a glider must reach flying speed, which is the speed at which the wings generate enough lift to overcome the force of gravity. With the early gliders, the flying speed was very low, and most gliders took off into a wind. In appearance, modern gliders look much like an ordinary airplane but are extremely light. They have low wing loading (the ratio of weight to wing area) and a high aspect ratio (the ratio of the wingspan to the wing width).
The 1902 Wright glider
Credits - Wright State University
Experiments with gliders laid the foundation for the design of the first powered aircraft. Early glider pioneers included Sir George Cayley, Jean-Marie Le Bris, Otto Lilienthal, Octave Chanute, Orville and Wilbur Wright, and John Joseph Montgomery.