Leonardo da Vinci's flapping-wing flying-machine concept was an ornithopter.
An ornithopter is an aircraft intended to fly by moving its wings up and down, rather than by using a propeller or a jet engine. Leonardo studied birds and bats extensively and drew several human-powered flying-machine designs during the late fifteenth century. His sketches included wing frames, harnesses, pedals, and mechanisms intended to transfer human movement to the wings.
Leonardo's machines were never proven to fly. A human could not generate enough sustained power with the muscles available to operate such large wings, and the proposed structures would also have been heavy. Nevertheless, his drawings show careful attention to anatomy, balance, airflow, and mechanical transmission.
Ornithopters are not the same as gliders. A glider has fixed wings and remains aloft by moving through air, while an ornithopter relies on flapping motion. Leonardo's work is remembered as an influential early study of biological flight and mechanical flight, not as a successful aircraft prototype.