DRS stands for Drag Reduction System. It is an addition to the rear wing of the car introduced in 2011 Formula 1 season aimed at reducing aerodynamic drag in order to promote overtaking. It is used when a driver is close to somebody in front of him. He will be able to open the rear wing so the car becomes more streamline and aerodynamic so he can overtake his opponent. The device is then disabled as soon as he overtakes his opponent.