Play is a rite an a quality of mind in engaging with one's worldview. Play may consist of amusing, pretend or imaginary interpersonal and intrapersonal interactions or interplay. The rites of play are evident throughout nature and are perceived in people and animals, particularly in the cognitive development and socialization of children. Play often entertains props, animals, or toys in the context of learning and recreation. Some play has clearly defined goals and when structured with rules is entitled a game, whereas some play exhibits no such goals nor rules and is considered to be "unstructured" in the literature.