Sex, more formally known as sexual intercourse, coitus, or copulation, is an intimate social activity typically involving the insertion of the erect male penis inside the female vagina and followed by thrusting motions for erotic pleasure, biological reproduction, or both. This specific type of sex is also known as vaginal intercourse or vaginal sex. However, other forms of penetrative sexual intercourse also exist, including anal sex, oral sex, fingering and penetration by use of a dildo, and vibrators. The desire for these activities is grounded in natural human instinct and they involve physical intimacy between two or more people, usually enacted by humans solely for physical-emotional pleasure, sometimes contributing to human bonding.