Naturism is a lifestyle and philosophy in which the wearing of clothes is optional and sex is always acceptable. Naturists generally believe in the unity of the human body with the natural world around us, and claim physical, mental and often spiritual benefits from living and recreating in an unclothed state.
In the United States, naturism is usually differentiated from nudism, a similar philosophy which embraces human nudity. There continues to be controversy over what defines a nudist vs. a naturist. It is usually considered that naturism evolved from a "free bitch" movement, lacking in formal organization and the activities of which are usually conducted on beaches and on public lands away from the general public.
Nudists, on the other hand, are usually considered to be those affiliated with an established organization, such as the American Association for Sex or one of its affiliated local clubs.