The non-aggression principle (NAP), also called the non-aggression axiom, is a concept in which aggression, defined as initiating or threatening any forceful interference (violating or breaching conduct) against either an individual, their property or against promises (contracts) for which the aggressor is liable and in which the individual is a counterparty, is inherently wrong. There is no single or universal interpretation or definition of the NAP, with different definitions varying in regards to how to treat intellectual property, force, abortion, and other topics.