Masturbation is the sexual stimulation of one's own genitals for sexual arousal or other sexual pleasure, usually to the point of orgasm. The stimulation may involve hands, fingers, everyday objects, sex toys such as vibrators, or combinations of these. Mutual masturbation (mutual manual stimulation of the genitals between partners) can be a substitute for sexual penetration. Studies have found that masturbation is frequent in humans of both sexes and all ages, although there is variation. Various medical and psychological benefits have been attributed to a healthy attitude toward sexual activity in general and to masturbation in particular. No causal relationship is known between masturbation and any form of mental or physical disorder.