Dog agility is a sport in which a handler directs a dog through an obstacle course in a race for both time and accuracy. Dogs must run off-leash with no food or toys as incentives. The handler can touch neither dog nor obstacles, except accidentally. Consequently, the handler's controls are limited to voice, movement, and various body signals, requiring exceptional training of the animal and of the human.
In its simplest form, an agility course consists of a set of standard obstacles, laid out by an agility judge in a design of his own choosing on a roughly 100 by 100 foot (30 by 30 m) area, with numbers indicating the order in which the dog must complete the obstacles.
Courses are complicated enough that a dog could not complete them correctly without human direction. In competition, the handler must assess the course, decide on handling strategies, and direct the dog through the course, with precision and speed equally important. Many strategies exist to compensate for the inherent difference in human and dog speeds and the strengths and weaknesses of the various dogs and handlers. Many things can go wrong, though, and for any course on any day, it is rare to be able to predict which team will perform best.