The empennage, also known as the tail or tail assembly, provides stability for aircraft, in a way similar to the feathers on an arrow. The term derives from the French language word empenner which means “to feather an arrow”. Most aircraft feature an empennage incorporating vertical and horizontal stabilising surfaces which stabilise the flight dynamics of yaw and pitch, as well as housing control surfaces.

In spite of effective control surfaces, many early aircraft that lacked a stabilising empennage were virtually unflyable. Even so-called “tailless aircraft” usually have a tail fin (vertical stabiliser). Heavier-than-air aircraft without any kind of empennage (such as the Northrop B-2) are rare. (source)