Signalling flags

In order to guarantee on track driver safety at any moment during a race weekend the FIA prescribes several ways of signalling drivers that there is something unusual happening somewhere on the course. The most obvious and important of these measures are 10 flags that have a well known meaning, not only in Formula One but also widely known in all FIA motorsports and other racing series that are not governed by the FIA.

	A yellow flag is a general sign to notify drivers of a dangerous situation on the track that is not caused by themself. A single yellow indicates danger ahead, such as debris from a crash. Drivers must slow down as they pass; no overtaking is permitted. A double yellow, consisting of two flagmen waving yellow flags (or one waving two flags) at the same post, indicates great danger ahead. Drivers must slow down and be prepared to stop; no overtaking is permitted. A yellow flag accompanied with a white sign with SC in black written on denotes that the safety car is on track and that overtaking is forbidden for the duration of the safety car period. A safety car is often used to allow the circuit crew to clear wreckage and clean the track for further racing.
	A red flag with yellow stripes warns the driver of a slippery track and is demanded to slow down for his own safety.
	A white flag indicates a slow-moving vehicle such as an ambulance, tow truck, or safety car, ahead on the track, and instructs drivers to slow down. (It is NOT waved at the start of the final lap of the race.)
	Race stopped early or temporarely stopped because of an extremely high danger.
	A light blue flag may carry any of three meanings according to its context. At any time, a stationary light blue flag (or, as is now more common, a blue light) may be shown to a driver at the pitlane exit to warn him that cars are approaching on the track. During practice, a light blue flag waved on the track notifies a driver that a faster car is about to pass him and he must move aside. During a race, a light blue flag waved on the track warns the driver that he is about to be lapped by a faster car and must let it pass. A driver may incur penalties if he ignores three successive blue flags.
	Circuit is free from danger. All previous danger warnings are not anymore appropriate.
	A half black and half white flag informs a driver that his behavior has been deemed unsporting and if he does not shape up immediately he will be disqualified. A sign with the car number accompanies the flag. Driver can be punished with a ten second penalty or he can be shown a black flag.
	A black flag orders a particular driver to return to his pit within the next lap and report immediately to the Clerk of the Course, usually because he has been disqualified from the race. The flag is accompanied by a sign with the car number of the driver on it so no mistake is made.
	A black flag with an orange circle (40cm in diameter) in the center informs a driver that his team's telemetry has sensed a technical problem and he must return to his pit.
	End of the race. Finish

Flags, whose specifications are prescribed by the FIA International Sporting Code, must measure at least 60cm by 80cm, excepting the red and chequered flags, which must measure at least 80cm by 100cm.

Driver aids

In order to further improve safety on the track, drivers are in constant contact with their team so that they can quickly inform about an accident or any other dangerous situation on the track. Every F1 car is also equipped with a yellow led on the steering wheel that is switched on when a yellow flag is waved somewhere on the circuit. In case radio contact would be troublesome, the driver is still aware caution is needed, even well ahead of the dangerous area.