Adultery is extramarital sex, in which a spouse has intercourse with someone outside the marriage. Historically, this has been regarded primarily as a moral issue, rather than a legal one. Proof of adultery is grounds for divorce, however, and in some regions of the world it may be punishable by law. Attitudes about adultery vary between cultures and between groups within larger societies, and personal beliefs about it are often based in religious values.
In order to be considered adultery, the contact must be consensual in nature and clearly sexual. Simply flirting, for example, is not adultery, but sexual contact is. It may occur once or on multiple occasions. Also known as philandery, infidelity, or an affair, adultery may involve an emotional connection with the partner outside the marriage, or the relationship may be purely sexual.
In many cultures, people believe that marriage is a sacrament between two people, and adultery is subsequently frowned upon. Some people engage in open marriages, however, in which they are committed to a primary partner in the form of a spouse, and one or both partners have sexual relationships with others by agreement with the primary partner. Swinging communities are one example of how open marriages can work.
While adultery may not necessarily come with legal punishments, in some cultures it can result in social stigma. Some regions of the world also practice honor killing, in which the unfaithful spouse and the adulterer are killed. Other forms of punishment, such as throwing acid in the face of an adulterous spouse, have also been documented. More commonly, however, adultery ends in counseling, and the partners may explore the possibility of a divorce if they feel that they are no longer suited to each other.
It is difficult to obtain accurate statistics on adultery. Some people may be afraid to admit to extramarital affairs, even in confidential surveys, and cultural differences between people conducting surveys and their subjects may also create barriers. Studies which have been conducted seem to suggest that infidelity is not uncommon, however.
In a legal context, in addition to being grounds for divorce, affairs can sometimes trigger certain clauses in a prenuptial agreement. For example, the agreement may specify that an adulterous spouse is not entitled to an equal division of assets in the event of a divorce. While couples can file for a no-fault divorce, the adultery can still be brought up during the process of reaching a settlement agreement.