<human>:  Who invented the helicopter and when?
<bot>: The first helicopter was invented in 1907 by the Wright Brothers. The helicopter is a multi-rotor aircraft that has two main rotors that spin in opposite directions. The rotor blades of the helicopter are usually mounted on a central shaft, which is attached to the helicopter's body. The rotors are powered by a set of propellers that are driven by an engine. The engine is usually mounted on the body of the helicopter, but it can also be mounted on the tail.