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/her own choosing on a roughly 100 by 100 foot area, with numbers indicating the order in which the dog must complete the obstacles.

In competition, the handler must analyze the course, decide on handling strategies, and direct the dog through the course. Precision and speed are 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.

Because each course is different, handlers are allowed a short walk-through before the competition starts. During this time, all handlers competing in a particular class can walk or run around the course without their dogs, determining how they can best position themselves and guide their dogs to get the most accurate and rapid path around the numbered obstacles.

The walk-through is critical for success because the course's path takes various turns. The course may take a U turn, cross back on itself, use the same obstacle more than once, have two obstacles so close to each other that the dog and handler must be able to clearly "discriminate" which to take. The course can even be arranged so that the handler must work with obstacles between himself and the dog or at a great distance from the dog.

Printed maps of the agility course are often made available to the handlers before they run, to help the handlers plan their course strategy. The course map contains icons indicating the position and orientation of all the obstacles, and numbers indicating the order in which the obstacles are to be taken.

Each dog and handler team gets one opportunity to attempt to complete the course successfully. The dog begins behind a starting line and, when instructed by his handler, proceeds around the course. The handler typically runs near the dog, directing the dog with spoken commands and with body language (the position of head, arms, shoulders, and feet).