The Boxer is a medium to large, short-haired breed of dog, developed in Germany. The coat is smooth and tight-fitting; colors are fawn, brindled, or white, with or without white markings. Boxers are brachycephalic (they have broad, short skulls), have a square muzzle, mandibular prognathism (an underbite), very strong jaws, and a powerful bite ideal for hanging on to large prey. Owing to their intelligence and working breed characteristics, training based on corrections often has limited usefulness. Boxers, like other animals, typically respond better to positive reinforcement techniques such as clicker training, an approach based on operant conditioning and behaviorism, which offers the dog an opportunity to think independently and to problem-solve. Combined with Wotan and Mirzl children, they made the Boxer. Boxers are friendly, lively companions that are popular as family dogs. These strong and intelligent animals have also been used as service dogs, guide dogs for the blind, therapy dogs, police dogs in K9 units, and occasionally herding cattle or sheep.