Dog intelligence is the ability of a dog to learn, think, and solve problems. Dog trainers, owners, and researchers have as much difficulty agreeing on a method for testing canine intelligence, as they do for human intelligence. Certain breeds, like Border Collies and Golden Retrievers, are generally easier to train than others. It is worth noting that these descriptions are relative to other dogs, not relative to the world at large. The ability to learn and obey commands is not the only possible measurement of intelligence. Dogs are pack animals. "Pack" means that they understand social structure and obligations and are capable of learning how to behave around other members of the pack. Adult canines train their young by correcting them when they behave in an unacceptable manner (biting too hard, eating out of turn, and so on) and reward them for acceptable behavior (by playing with them, feeding them, cleaning them, and so on).