Green Flag

Starts the race or restarts the race.  Race under green.

Yellow Flag

Caution.  All cars must slow down to pace lap speed under yellow.  Usually due to an accident on the track or a car with mechanical trouble obstructing the track.

Green / Yellow

Continue to race, but be aware.  Usually used when a car is out of harms way, but near the race surface.

Red Flag

All cars must stop.

Black Flag

This flag is displayed to a car for a variety of reasons.  This may signify that the car is to go to the back of the field or may be given to direct the car off the track.

Black Flag with White X

This flag is know and the mechanical black flag, given to a car due to mechanical problems.

Blue Flag with Diagonal Yellow Stripe

This flag is given to a slower car to move over, normally when the car is going to be lapped by the lead cars and to make the driver aware he or she is about to be lapped.

White Flag

One lap to go.

Checker Flag

This flag ends the race.  It is given to the winner first and all competing cars finishing the race.