Horses have careers - some short, some long, some successful and some ugly. Many thoroughbreds born ("foaled") in a given year do not even make it to the racing scene at all. Of the thousands of horses born each year, only a tiny fraction wind up training for races at the track.

Not every horse is a champion. But since Race Secretaries seek to make every race a balanced one, clearly races need to be placed into a graded structure, so that champions will be pitted against other champs; the really hapless will get to race with horses at the same level; .and lots of races will be set up for all the horses in between. In addition, horses new to the scene are unproven, so there is a special category for them. If they show ability, they will move up quickly through the ranks. That is how the system works. Obviously, when a racing fan looks over a race card, the grade of the race will be very important for evaluating the qualities of the individual race entrants. Though the attention and the purse money rises for owners as their horses rise to "stakes" (championship) levels, the track tries to plan every race so that it is close. And a well-placed $2 bet in a low-grade race can win money that spends equally well as profits on the Kentucky Derby. In fact, "bargain bets" are often easier to find in the lower grade races, where the range of competitiveness may not be as narrow as it is at the very high levels.

The debut races are called "Maiden Races." The middle group are "claiming" and "allowance" races, and the top level is "stakes" races. The dividing lines are sometimes a bit blurred with some allowance races coming very close to the stakes level, for example. Each is covered in turn.