The Indianapolis 500, also formally known as the Indianapolis 500-Mile Race, or simply the Indy 500, is an annual automobile race held at Indianapolis Motor Speedway (IMS) in Speedway, Indiana, United States, an enclave suburb of Indianapolis. The event is traditionally held over Memorial Day weekend, usually the last weekend of May.

It is contested as part of the IndyCar Series, the top level of American Championship Car racing, an open-wheel, open-cockpit formula colloquially known as "Indy Car Racing". The track itself is nicknamed the "Brickyard", as the racing surface was paved in brick in the fall of 1909. One yard of brick remains exposed at the start/finish line.

The event, billed as The Greatest Spectacle in Racing, is considered part of the Triple Crown of Motorsport. The Triple Crown comprises three of the most prestigious motorsports events in the world, also including the Monaco Grand Prix (which traditionally falls on the same day as the Indianapolis 500) and the 24 Hours of Le Mans. In two different periods, the race was part of FIA World Championships; between 1925 and 1928, the World Manufacturers' Championship and between 1950 and 1960, the World Drivers' Championship. The official attendance is not disclosed by Speedway management, but the permanent seating capacity is upwards of 250,000, and infield patrons raise the race-day attendance to approximately 300,000. It shares its date with NASCAR's 600-mile event later in the evening at Charlotte, with drivers having completed both events in one day before in a so-called Double Duty. In addition, the Monaco Grand Prix (Formula One) is also held on the same date, a few hours earlier in Europe. As such, the last weekend of May is known as one of the largest weekends in auto racing.The inaugural race was held in 1911 and was won by Ray Harroun. The event celebrated its 100th anniversary in 2011, and the 100th running was held in 2016. The event was put on hiatus twice, from 1917 to 1918 due to World War I and from 1942 to 1945 due to World War II. Marcus Ericsson is the current champion. The most successful drivers are A. J. Foyt, Al Unser Sr., Rick Mears and Hlio Castroneves, each of whom has won the race four times. The active driver with the most victories is Hlio Castroneves. Rick Mears holds the record for most career pole positions with six. The most successful car owner is Roger Penske, owner of the Indianapolis Motor Speedway and Team Penske, which has 18 total wins and 18 poles. Penske also has five wins at the IndyCar Grand Prix, held on the combined road course.

The event is steeped in tradition, in pre-race ceremonies, post-race celebrations, and race procedure. The most noteworthy and most popular traditions are the 33-car field lining up three-wide for the start, the annual singing of the chorus of "Back Home Again in Indiana," and the victory lane bottle of milk. Also unique is that qualifying requires the driver to complete four, rather than one, timed laps. Qualifying has a separate weekend.

The Indianapolis Motor Speedway is an automobile racing circuit located in Speedway, Indiana (an enclave suburb of Indianapolis) in the United States. It is the home of the Indianapolis 500 and the Verizon 200, and formerly the home of the United States Grand Prix. It is the largest sports venue in the world. It is located on the corner of 16th Street and Georgetown Road, approximately six miles (9.7 km) west of Downtown Indianapolis.

Constructed in 1909, it is the second purpose-built, banked oval racing circuit after Brooklands and the first to be called a 'speedway'. It is the third-oldest permanent automobile race track in the world, behind Brooklands and the Milwaukee Mile. With a permanent seating capacity of 257,325, it is the highest-capacity sports venue in the world.Considered relatively flat by American standards, the track is a 2.5-mile-long (4.0 km) rectangular oval with dimensions that have remained essentially unchanged since its construction. It has two 5⁄8-mile-long (1,000 m) straightaways, four geometrically identical 1⁄4-mile (400 m) turns, connected by two 1⁄8-mile (200 m) short straightaways, termed "short chutes", between turns 1 and 2, and between turns 3 and 4.

A modern, FIA Grade One infield road course was completed in 2000, incorporating part of the oval, including the main stretch and the southeast turn, measuring 2.605 mi (4.192 km). In 2008, and again in 2014, the road course layout was modified to accommodate motorcycle racing, as well as to improve competition. Altogether, the current grounds have expanded from an original 320 acres (1.3 km2) on which the speedway was first built to cover an area of over 559 acres (2.3 km2). Placed on the National Register of Historic Places in 1975 and designated a National Historic Landmark in 1987, it is the only such site to be affiliated with automotive racing history.

In addition to the Indianapolis 500, the speedway also hosts NASCAR's Verizon 200 and Pennzoil 150. From 2000 to 2007, the speedway hosted the Formula One United States Grand Prix, and from 2008 to 2015 the Moto GP.

On the grounds of the speedway is the Indianapolis Motor Speedway Museum, which opened in 1956, and houses the Hall of Fame. The museum moved into its current building located in the infield in 1976. Also on the grounds is the Brickyard Crossing Golf Resort, which originally opened as the Speedway Golf Course in 1929. The golf course has 14 holes outside the track, along the backstretch, and four holes in the infield. The site is among the most visited attractions in Indianapolis, with 1 million guests annually. The speedway has served as the venue for the opening ceremonies for the 1987 Pan American Games. The track is nicknamed "The Brickyard" (see below), and the garage area is known as Gasoline Alley.

On November 4, 2019, Hulman & Company announced the sale of its company, including the Indianapolis Motor Speedway, the IndyCar Series and associated enterprises to Penske Corporation, owned by Roger Penske.