Horse racing has evolved from a primitive contest of speed and stamina to a sport involving large fields of runners, sophisticated electronic monitoring equipment, and immense sums of money. But the basic concept remains unchanged: The horse that crosses the finish line first is the winner. The earliest recorded horse races date to the Greek Olympic Games of 700 to 40 B.C.E. and later spread throughout Asia and Europe, with men riding on four-hitched chariots or bareback. In the 1500’s, when knights no longer needed their horses to carry hundreds of pounds of armor, hot-blooded European horses were shipped across the Atlantic to England to be crossed with native cold-blooded breeds for better speed and stamina. The result was the Thoroughbred racehorse. In the early days of racing, a race was simply a match race between two or at most three horses with a purse provided by their owners. When an owner withdrew, he forfeited half the prize money or even all of it. Agreements between owners and bettors were recorded by disinterested third parties known as keepers of the match book. In the 1729 publication An Historical List of All the Horse-Matches Run (1729) by John Cheny, this practice became formalized as a “play or pay” wager. A variety of distances are used for flat horse races around the world, but most important races in North America, including the Kentucky Derby, Preakness Stakes, Belmont Stakes and Dubai World Cup, are run over a range of 3.2 to 4.2 miles (6.4 to 8.2 km). Races shorter than this are generally considered sprints, while those lasting more than 2.4 miles are called route races or, in Europe, stayers. These races are referred to as ‘graded’ when the most important races are assigned a grade (I, II, or III) based on their importance, and they are ‘handicapped’ when weights are placed on individual horses based on their previous performance. Some races are open to all, while others are restricted by age or gender, such as a handicapped race for fillies and mares. Many of these horse races are sponsored by commercial firms and their names appear on the official program. The richest events offer purses in the millions of dollars. Ownership turnover is high in the horse racing business. This is why so many races are called claiming races. The winning horse can be purchased and taken by a new owner immediately after the race, leaving the previous owners without any control over where their animals end up. This practice is often criticized by animal rights groups. But many racehorses and their human caretakers develop deep, affectionate relationships that are cherished, nurtured, and respected by both sides. And although it is true that some former racehorses are euthanized, it’s important to note that this is relatively rare for these magnificent creatures. In fact, most retired racehorses find a fulfilling and happy second career as polo players, show jumpers or eventers.