A horse race is a sport, an event of great beauty, power and excitement that draws crowds to grandstands around the world. Bettors put money down on their favorite horse, hoping for a winning combination of skill and luck to pay off. Some people bet a few dollars per race, while others wager tens of thousands, or even millions of dollars.

The sport has evolved over the centuries, but its basic rules have not. The smallest detail can have the biggest impact on a race, and a rider’s ability to coax an advantage from his mount is a critical factor in victory. In the modern era of high-tech racing, horses are treated with the utmost care. Trainers use specialized training techniques to maximize a horse’s potential. Medications can help a horse perform at the top of his game. X-rays, MRI scanners and endoscopes can pick up a range of health problems before they become serious. 3D printing technology can create casts, splints and prosthetics for injured or sick horses.

One of the most important innovations in horse race has been a dramatic improvement in the safety of horses. Horses used to be exposed to the risk of injury and death by being thrown from a moving carriage. Now, horse races are run on paved tracks. There are still some dangerous situations, such as if a horse breaks down or becomes severely injured, but there are far fewer such incidents.

Before a race begins, the horse is led into a walking ring where the bettors check its coat for brightness and rippling to see if it is ready to run. A snarling, fidgeting horse is considered unfit to compete. Mongolian Groom was not snarling, but his lower legs were wrapped in blue bandages and he had a shadow roll across his nose, which cuts down on the number of shadows that can startle him.

Once a horse has passed the claiming ranks, it can compete in stakes races that offer class relief (a reduction in the weight a horse must carry to win). This ensures that horses of similar speed will be competing against each other, as opposed to running against slow horses or relegating a fast horse to a race where he would not be competitive.

In a stakes race, the entries close a certain amount of time in advance of the race. This is in contrast to a conditioned stakes race, where the nominations close several weeks or months ahead of the race. Fixed weights are assigned for each race based on the age, distance, sex and gender of the horse. This system was established in the 1750s by the British Jockey Club, which created standardized races for six-year-olds, five-year-olds and four-year-olds, with each race run over two 3-mile (4-km) heats. In addition, the race was limited to a maximum of three runners. This standardized system is the foundation for modern American thoroughbred horse races. It also has served as a model for other horse sports in other parts of the world.