The Yellow flagRace tracks have long used flags as a way for marshals to communicate with drivers. The colour and meaning of... There's more... is possibly the most important and most used flag during a race. It is used to inform the drivers used to direct the drivers about an immediate danger ahead, such as a collision, breakdown or obstruction on the track.
The DriverOK, so we all know what the driver is, right. I've always liked the description that F1 drivers are like... There's more... is required to reduce speed immediately and be prepared to take avoidance measures once the yellow flag is sighted. Racing resumes once a green flagThe green flag signals that the track is clear and drivers can race. The flag is used at the pit... There's more... is waived, usually at the marshal station immediately after the obstruction has been passed.
In addition to the yellow flag, tracks often signal with a flashing yellow LED light.