Aggression, in its broadest sense, is behavior, or a disposition towards behavior, that is forceful, hostile or attacking. It may occur either in retaliation or without provocation. In narrower definitions that are commonly used in psychology and other social and behavioral sciences, aggression involves an intention to cause harm, even if only as a means to an end. It has alternatively been defined as acts intended to increase relative social dominance. Predatory or defensive behavior between members of different species may not be considered aggression in the same sense. Aggression can take a variety of forms and can be physical or be communicated verbally or non-verbally