Sexual Intercourse

Sexual intercourse, also known as copulation or coitus, is commonly defined as the insertion of a male's penis into a female's vagina for the purposes of sexual pleasure, reproduction, or both. The term may also describe other sexual penetrative acts, such as anal sex, oral sex or fingering, or use of a strap-on dildo, which can be practiced by straight and gay or lesbian pairings, or multiple partners.

Sexual intercourse can play a strong role in human bonding, often being used solely for pleasure and leading to stronger emotional bonds, and there are a variety of views concerning what constitutes sexual intercourse or other sexual activity. For example, non-penetrative sex (such as non-penetrative cunnilingus) has been referred to as "outercourse", but may also be among the sexual acts contributing to human bonding and considered intercourse. The term sex, often a shorthand for sexual intercourse, can be taken to mean any form of sexual activity (i.e. all forms of intercourse and outercourse). Because individuals can be at risk of contracting sexually transmitted diseases during these activities, although the transmission risk is significantly reduced during non-penetrative sex, safe sex practices are advised.

In human societies, some jurisdictions have placed various restrictive laws against certain sexual activities, such as sex with minors, incest, extramarital sex, position-of-trust sex, prostitution, sodomy, public lewdness, rape, and bestiality. Religious beliefs can play a role in decisions about sex, or its purpose, as well; for example, beliefs about what sexual acts constitute virginity loss or the decision to make a virginity pledge. Some sections of Christianity commonly view sex between a married couple for the purpose of reproduction as holy, while other sections may not. Modern Judaism and Islam view sexual intercourse between husband and wife as a spiritual and edifying action. Hinduism and Buddhism views on sexuality have differing interpretations.

Sexual intercourse between non-human animals is more often referred to as copulation; for most, mating and copulation occurs at the point of estrus (the most fertile period of time in the female's reproductive cycle), which increases the chances of successful impregnation. However, bonobos, dolphins, and chimpanzees are known to engage in sexual intercourse even when the female is not in estrus, and to engage in sex acts with same-sex partners. Like humans engaging in sex primarily for pleasure, this behavior in the above mentioned animals is also presumed to be for pleasure, and a contributing factor to strengthening their social bonds.