Clicker training can be an excellent method of positive reinforcment training for animals. It usually involves the use of a flat, springy piece of metal that 'clicks' when you press down and release it. Other sounds and devices can achieve about the same results, depending on the personality and temperament of the animal. It is used as part of a method of positive reinforcement where the animal initially is exposed to the sound or positive stimulus, and immediately afterwards gets a treat, or praise, or just about anything that really makes it happy. It gets used to the sound or stimulus as being a very good thing. Next, the trainer makes the 'click' at the exact moment the animal is doing something that the trainer wants to reinforce, so that the animal will repeat it. As it soon picks up the fact that the particular behavior is getting rewarded, it will starting 'offering' the behavior, or repeating it more often, to get more 'treats'! It works very well for very many different animals, most of which you would think are 'untrainable' by previous modern standards. Best of all, both the handler and the animal are in a happy state of mind, whereas older methods of animal training often involve(d) coercion, forcing movement, etc.
The person who wrote the book I use for training Calen originally used to be a dolphin trainer. She found out that this method is the most effective way to instruct an animal (including humans) without having to force postures and behaviors. The animal soon learns that it has control over its being rewarded, and will soon offer different behaviors in hopes of doing the one that will get it the treat. Their mental focus is sharpened, their alertness and confidence greatly increased, and they may start relating to their owner/trainer as someone that is enjoyable to be around, instead of someone to be dreaded except at dinnertime and bathroom breaks. What both the trainer and the trainee can learn is limited only by the trainers' creativity and willingness to think through the lessons and plan them out thoroughly. (more on this soon!)