As sophisticated as auto racing has become with spotters, computer links and radio communications, the key to understanding what is happening on the track is the flags used by race officials and corner marshals (corner workers).

Drivers rely on the flags to tell them what is happening during practice, qualifying and racing. As a spectator, either at the track or via television, you can tell what's happening as soon as you see a flag. It only takes a few minutes to learn what the different flags mean.

While many of the flags have similar meanings, there are variations between racing series and, sometimes, from track to track. Meaning also can differ depending on how the flag is held. A stationary flag can have one meaning while the waving flag can have another. It's up to the race officials and corner workers to make sure the proper flag is used and held or waved appropriately.

The following guide to auto racing flags includes the most commonly used meanings. Racers and team members should always check their individual series rule book and ask at the track for any variations.

Yellow Flag - Caution

The yellow flag is the signal for caution. When it is held stationary it is an indication that there is a problem ahead. Drivers must slow and refrain from passing. A waving yellow flag indicates immediate danger ahead. Drivers must be prepared to stop and cannot pass, although they can close the distance to the car immediately in front. Yellow flags can indicate problems in one area of a track when waved by only one or two corner workers. A "full course caution" (or yellow) is when all flags around the track are being waved. This is initiated by the starter. Passing under the yellow is a serious infraction and drivers may be severely punished. When a driver is penalized for passing under yellow it is often a controversial call and may be appealed.

 Red Flag - Stop!

When a race is "red flagged" it is stopped due to some condition that has made the track unraceable. These conditions can range from weather problems to accidents to surface problems such as oil on the track. A red flag often means the track has been completely blocked by an accident or debris and there is no safe route through the problem. The red flag generally is preceded by waving yellow flags. As soon as a red flag is shown, drivers must come to a stop as quickly and safely as possible. Each series has different rules on what drivers and teams can do during a red flag stop and how the restart is handled.

White Flag - Last Lap

When waved by the starter the white flag indicates that a driver is entering the last lap of practice, qualifying or a race. It is waved continuously to all cars following the leader until the leader approaches the finish line. In some areas the white flag is used by corner workers to indicate an ambulance or slow moving vehicle on the track. To avoid confusion, some tracks use a white flag with red cross to indicate an ambulance is on the track or needed.

Checkered Flag - Finish Line

One of the most familiar symbols worldwide, the checkered flag says "racing!" It is waved by the starter to indicate the finish of the race or practice session. The checkered flag is waved for all finishers. The race winner usually collects a checkered flag for a victory lap around the track. In many race series the checkered flag has the race logo embroidered on the flag and it is given to the winner as a memento.