The 24 Hours of Le Mans (French: 24 Heures du Mans) is the world's oldest active sports car race in endurance racing, held annually since 1923 near the town of Le Mans, France.[1] It is one of the most prestigious automobile races in the world and is often called the "Grand Prix of Endurance and Efficiency".

Racing teams have to balance speed with the cars' ability to race for 24 hours without sustaining mechanical damage, and manage the cars' consumables, primarily fuel, tyres, and braking materials. It also tests endurance, with drivers frequently racing for over two hours before a relief driver can take over during a pit stop while they eat and rest. Current regulations mandate that three drivers share each competing vehicle.

The race is organised by the Automobile Club de l'Ouest (ACO) and runs on the Circuit de la Sarthe, which contains a mix of closed public roads and a specialist racing circuit that tests both speed and endurance. Competing teams race in groups called "classes", or cars of similar specification, while also competing simultaneously for outright placing amongst all classes. Originally, the race showcased cars as they were sold to the general public, then called "Sports Cars", compared to the specialised racing cars used in Grand Prix motor racing. Over time, the competing vehicles evolved away from their publicly available road car roots, and today the race is made of two classes—enclosed-bodywork two-seat prototypes, and two classes of Grand Touring cars similar to sports cars sold to the public).[2]

Competing teams have had a wide variety of organisation, ranging from competition departments of road car manufacturers (eager to prove the supremacy of their products) to professional motor racing teams (representing their commercial backers, some of which are also car manufacturers who want to win without paying for their own teams) to amateur teams (racing as much to compete in the famous race as to claim victory for their commercial partners).

The race is held in June, leading at times to very hot conditions for drivers, particularly in closed vehicles with poor ventilation; rain is not uncommon. The race begins in mid-afternoon and finishes the next day, at the same hour the race started.[3] Over the 24 hours, modern competitors often cover distances well over 5,000 km (3,110 mi). The record is 2010's 5,410 km (3,360 mi),six times the length of the Indianapolis 500, or approximately 18 times longer than a Formula One Grand Prix.[4]

The race has over the years inspired imitating races all over the globe, popularising the 24-hour format at places like Daytona, Nürburgring, Spa-Francorchamps, and Bathurst. The American Le Mans Series and Europe's Le Mans Series of multi-event sports car championships were spun off from 24 Hours of Le Mans regulations. Other races include the Le Mans Classic, a race for historic Le Mans race cars of years past held on the Circuit de la Sarthe, a motorcycle version of the race which is held on the shortened Bugatti version of the same circuit, a kart race (24 Heures Karting), and a truck race (24 Heures Camions).

The race has also spent long periods as a round of the World Sportscar Championship, although Le Mans has always had a stronger reputation than the World Championship, and is a round of the FIA World Endurance Championship. The race is also known as a leg of the informal Triple Crown of Motorsport which links Formula One, IndyCar, and sports car racing to represent a career achievement for drivers. Additionally, it is seen as a leg of the Triple Crown of endurance racing, which links the three largest sports car races together, with 12 Hours of Sebring and 24 Hours of Daytona forming the other legs. Since 1998, the American Le Mans Series held a second endurance race along with the 12 hours of Sebring every year called "Petit Le Mans" Petit Le Mans, as a 10-hour or 1,000-mile American version. In 2014, the Tudor Sports Car Championship (a merger of the races at Sebring, Petit Le Mans in Braselton, Georgia, and the Rolex Sports Car Series' 24 Hours of Daytona) held all three American races in preparation for teams to race at Le Mans.