Wondering what the different flags signal during a NASCAR race? Here's a quick guide to the different colors that are used to alert drivers:

Green: Used to signal the beginning of the race and restarts, the green flag tells drivers the track is clear and they may resume at high speeds.

Yellow: The yellow, or caution, flag alerts drivers to an accident, debris or weather issues. During a race, cars will bunch up behind the leader until the track is safe. At practice, cars immediately return to their pits.

Red: The red flag tells drivers the track is unsafe or there is situation that requires immediate attention. The flag is usually waves if there is heavy precipitation, if the track is blocked or if there is an accident that requires medical attention. When the red flag is shown, cars must stop in a designated location.

White: The white flag is waved to tell drivers there is one lap remaining in the race.

Checkered: The checkered flag is waved at the end of the race.

Black: The black flag is usually waved at an individual driver to alert them to go to the pits -- usually because of a mechanical problem or a rules violation. During a practice session, the waving of the black flag in combination with the red flag signals the end of a practice session.

Black With White Cross: The black flag with a white cross is waved if a driver fails to acknowledge the black flag.

Blue With Yellow Stripe: The blue flag with yellow stripe is waved to tell a driver that a faster car is approaching from behind and they should pay attention to their mirrors.

Yellow With Red Vertical Stripes: The yellow flag with red vertical stripes is used only on road courses for corner workers to alert drivers to debris or slippery conditions.