Masturbation refers to sexual stimulation, especially of one's own genitals and often to the point of orgasm, which is performed manually, by other types of bodily contact (except for sexual intercourse), by use of objects or tools, or by some combination of these methods. Masturbation is the most common form of autoeroticism, and the two words are often used as synonyms, although masturbation with a partner (mutual masturbation) is also common. Animal masturbation has been observed in many species, both in the wild and in captivity.