What is the hop up?

Have you ever ask yourself what is the hop up. Well I am going to teach you. The hop up is a tool that is in your gun that you adjust, no all weapon have the hop up. The hop up will let you shoot straight, curve or the bb will rise to the sky if move your hop up down the BB won't far if you moved up it will rise to the sky but if you adjusted right it will go far and straight