Voluntaryism is first and foremost a moral philosophy which states that all interactions between people are morally acceptable if they are voluntary, i.e., mutually agreed upon. Interactions in which one party does not agree to the interaction are considered coercive as opposed to voluntary, and are morally unacceptable. In this sense, voluntaryism is a "rebranding" of the more well-known and traditional libertarian principle, the non-aggression principle, which states that the only time coercion is morally justified is when it is being used to prevent coercion - initiation of coercion, or aggression, is immoral. Both methods of explaining the principles of libertarian philosophies are ancillary to property rights, which are generally explained by the the principle of self-ownership and ownership of the products of one's own labor.
See also: libertarianism, minarchism, anarcho-capitalism, autarchism, agorism, market anarchism.