Marriage is a socially supported union involving two or more individuals in what is regarded as a stable, enduring arrangement based at least in part on a sexual bond of some kind. Depending on the society, marriage may require religious and/or civil sanction, although some couples may come to be considered married simply by living together for a period of time (common law marriage). Though marriage ceremonies, rules, and roles may differ from one society to another, marriage is considered a cultural universal, which means that it is present as a social institution in all cultures. Marriage serves several functions. In most societies, it serves to socially identify children by defining kinship ties to a mother, father, and extended relatives. It also serves to regulate sexual behavior, to transfer, preserve, or consolidate property, prestige, and power, and most importantly, it is the basis for the institution of the family. In most societies, a marriage is considered a permanent social and legal contract and relationship between two people that is based on mutual rights and obligations among the spouses. A marriage is often based on a romantic relationship, though this is not always the case. But regardless, it typically signals a sexual relationship between two people. A marriage, however, does not simply exist between the married partners, but rather, is codified as a social institution in legal, economic, social, and spiritual/religious ways. Typically a the institution of marriage begins with a period of courtship that culminates in an invitation to marry. This is followed by the marriage ceremony, during which mutual rights and responsibilities may be specifically stated and agreed to. In many places the state must sanction a marriage in order for it to be considered valid and legal, and also in many cultures, a religious authority must do the same. In many societies, including the Western world and the United States, marriage is widely considered the basis of and foundation for family. This is why a marriage is often greeted socially with immediate expectations that the couple will produce children, and why children that are born outside of marriage are often branded with the stigma of illegitimacy. Because a marriage is recognized by law, by the economy, socially, and by religious institutions, a dissolution of marriage (annulment or divorce) must, in turn, involve a dissolution of the marriage relationship in all of these realms. Marriage has several social functions that are important within the societies and cultures where the marriage takes place. Most commonly, marriage dictates the roles that spouses play in each other’s lives, in the family, and in society at large. Typically these roles involve a division of labor between the spouses, such that each is responsible for different tasks that are necessary within the family. American sociologist Talcott Parsons wrote on this topic and outlined a theory of roles within a marriage and household, wherein wives/mothers play the expressive role of a caregiver who takes care of socialization and emotional needs of others in the family, while the husband/father is responsible for the task role of earning money to support the family. In keeping with this thinking, a marriage often serves the function of dictating the social status of the spouses and the couple, and of creating a hierarchy of power between the couple. Societies in which the husband/father holds the most power in the marriage are known as patriarchies. Conversely, matriarchal societies are those in which wives/mothers hold the most power. Marriage also serves the social function of determining family names and lines of familial descent. In the U.S. and much of the Western world, we practice patrilineal descent, meaning the family name follows that of the husband/father. However, many cultures, including some within Europe and many in Central and Latin America, follow matrilineal descent. Today, it is common for newly married couples to create a hyphenated family name that preserves the named lineage of both sides, and for children to bear the surnames of both parents.