In Formula 1 car racing, what colour flag is shown during a race to warn the driver that he is about to be lapped by a faster car?

The numerous Formula One regulations, made and enforced by the Federation Internationale de l'Automobile (FIA) and later the Federation Internationale du Sport Automobile (FISA), have changed dramatically since the first Formula One World Championship in 1950.

Many venues make use of electronic displays to indicate flags to give various messages to drivers. However, race marshals continue to use physical flags as a redundancy mechanism in the event of electronic display failure. Marshals are positioned at numerous points around the track during every race. Flags have different meanings depending on their colour;

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 not intentionally impede their progress, such as blocking a passing manoeuver. A driver may incur penalties if he ignores three successive blue flags.