DRS stands for Drag Reduction System, which is a driver-controlled device aimed at aiding overtaking and increasing the chances of wheel-to-wheel racing in Formula 1. It was introduced in 2011 to make overtaking easier. The system involves the driver opening a flap in their rear wing to reduce drag levels and gain top speed when running within a second of a car in front. The flap is an integral part of the wing creating downforce, but it can be moved to an "open" horizontal position when the driver pushes a button on the steering wheel. This reduces drag and increases top speed, allowing for a performance advantage on a circuits straightaways. DRS can be used by a driver who is within one second of the car ahead, and this is allowed when a driver is running within one second of a car ahead – even if this car is being lapped. In practice and qualifying, DRS can be used at will, but only within the set activation zones.