A retriever is a type of gun dog that retrieves game for a hunter. Generally gun dogs are divided into three major classifications: retrievers, flushing spaniels, and pointing breeds. Retrievers were bred primarily to retrieve birds or other prey and return them to the hunter without damage; retrievers are distinguished in that nonslip retrieval is their primary function. As a result, retriever breeds are bred for soft mouths and a great willingness to please, learn, and obey. A soft mouth refers to the willingness of the dog to carry game in its mouth without biting into it. "Hard mouth" is a serious fault in a hunting dog and is very difficult to correct. A hard-mouthed dog renders game unpresentable or at worst inedible.