Sexual intercourse is a sexual activity involving the insertion and thrusting of the male penis inside the female vagina for sexual pleasure, reproduction, or both. This is also known as vaginal intercourse or vaginal sex. Sexual penetration has been known by humans since the dawn of time, and has been an instinctive form of sexual behaviour and psychology among humans. Other forms of penetrative sexual intercourse include anal sex, oral sex, fingering and penetration by use of a dildo, and vibrators. These activities involve physical intimacy between two or more people and are usually used among humans solely for physical or emotional pleasure. They can contribute to human bonding.