Throughout history horse races have been held as a form of entertainment. These races can take place on the flat or over a course of jumps, and they can be run on turf or sand. Spectators often bet on the horses, and many of these races are profitable. A horse race is a competition between horses over a specified distance, usually of two to four miles (3.2 km-3,200-6,400 m). The races are run on flat tracks or courses of jumps that include hurdles and fences. The race begins at a starting gate or stalls, and the rider and the horse must navigate the course without being hampered by other horses. The first to cross the finish line wins. In most races, the winner is determined by a combination of skill and luck. This is reflected in the way that the jockeys ride their horses, their ability to predict where the other horses will go and to coax them over the obstacles. Most horse races are won by the fastest horses in a field of ten or more, and these horses may be called the front runners. The horses are ridden by experienced riders, who may be accompanied by support staff. A few races are won by horses who have no apparent speed advantage. These are known as ‘jumping’ or’staying’ races. These are often run over longer distances than the other types of races. Some people believe that the sport is not a good one for horses, as it can cause a number of injuries. In particular, the pressure on the horses’ developing bones and ligaments is far too great, and the drugs used to boost their performance are sometimes dangerous. Another problem is that most of the horses in the sport are bred for speed rather than stamina. This means that the horses have less chance to repair their injuries and are not as hardy. Nevertheless, racing is an important part of the world’s economy. The racing industry generates over $80 billion in annual revenue, and it employs more than a million people worldwide. The sport has a long tradition in many countries, including the United States and Britain. It has a large following, with many people attending races in person or watching on television. In the United States, the major racing tracks are Churchill Downs, Saratoga Raceway, and Santa Anita Park. There are also smaller, regional tracks and racing venues. There are many different breeds of horse, each with its own characteristics and temperament. Some of the more popular ones include the Thoroughbred and the Standardbred. A horse’s athletic potential is influenced by several genes and is largely polygenic. Among these are the MSTN loci, which affect early skeletal muscle development and the ability to race at short distances. Because of these genetic and environmental factors, some animals are able to excel at racing while others do not. There are a number of factors that can make it difficult for a horse to develop a reputation as a strong performer, such as poor nutrition and inadequate exercise. In addition, there are some conditions, such as exercise-induced pulmonary hemorrhage, that can lead to death or even serious injury.