Animal training refers to teaching animals to perform specific acts in response to specific conditions or stimuli. Training may be for the purpose of companionship, detection, protection, or entertainment.An animal trainer may use reinforcement or punishment to condition an animal's responses. Some animal trainers may have a knowledge of the principles of behavior analysis and operant conditioning, but there are many ways to train animals and no legal requirements or certifications are required.The certifying bodies that do exist (in some, not all, countries) do not share consistent goals or requirements so it can be difficult to tell what kind of training a trainer has had to do his or her job. The United States does not require animal trainers to have any kind of certification or psychological screening. Unfortunately, the use of physical force and pain are all too often intrinsic in animal training.The type of training is often determined by the trainer's motivation, background, and psychological make-up. An individual training a seeing eye dog, for example, will have a different approach and end-goal than an individual training a wild animal to do tricks in a circus.Ideally, animal trainers will try to use positive reinforcement (follow a desired behavior with something worthwhile to the animal and the behavior will increase) and negative punishment (withdraw something the animal wants when he performs undersirable behaviors). Traditional trainers often rely on positive punishment (follow an undesirable behavior with a punishment to reduce the rate of the behavior) and negative reinforcement (withdraw an undesirable stimulus when the animal performs the desirable behavior).