A cutaway of Matt Kenseths car shows the steel roll cage that is part of the chassis.
BACKMARKER: A car at or near the back of the field.
BANKING: The sloping of the track surface, measured in degrees from horizontal.
CARBURETION DAY: The final practice before the Indianapolis 500, usually on the Thursday before the race.
CAUTION: A period of a race when the field is required to slow behind the pace car, and passing is not allowed. Cautions result from an accident, an oil leak, rain or other trouble on the track.
CHASSIS: The frame and suspension of a car.
DOWNFORCE: The aerodynamic pressure pushing the car down on the track.
DRAFTING: A driver's use of the car ahead of him or her to break wind resistance and gain momentum.
GRIP: Tire traction on the track.
GROOVE: The best route around the racing surface.
HANS: The Head and Neck Safety device, which became famous after Dale Earnhardt's death at Daytona. The brace fits around the shoulders and attaches to a driver's helmet, limiting neck movement during a crash to help minimize whiplash.
HAPPY HOUR: The final hour of practice during which faster laps often occur because the track is cooler.
INTERMEDIATE TRACK: A track measuring 1 mile or more, but no longer than 2 miles around.
LOOSE: A car is loose when the rear is unstable because of improper rear tire grip. Also known as oversteer.
MARBLES: Small pieces of tire rubber that build up above the racing groove.
ON THE BUBBLE: After the race field is full but qualifying hasn't ended, the slowest qualifier, the one who could be bumped from the field, is on the bubble.
OPEN WHEEL: Fenderless cars that race with their wheels exposed. Includes Champ Cars, IndyCars, Formula One and sprint cars.
PUSHING: The car resists turning because of a lack of grip. Also known as understeer.
RESTRICTOR PLATES: NASCAR adopted them in 1987 after Bobby Allison's car flew into the catch fence at Talladega. They are used at the two longest and potentially fastest tracks, Talladega and Daytona. The plates cut the airflow to the engine, reducing speeds that had reached well over 200 mph.
SLICK: A condition in which tires have trouble gripping the track, but is not limited to oil or water. Also refers to a grooveless tire.
STICKERS: Term for new tires, which still have the manufacturer's stickers on them.
STREET COURSE: A race track laid out at least partly on city streets, such as the one near the Bayfront Center for the Grand Prix of St. Petersburg.
TELEMETRY: Radio device that relays information about the engine, tires, steering and throttle performance to crew members.