Final answer:
Marriage is a legally recognized social contract between two people based on a sexual relationship and a sense of permanence. It can have variations across societies and can be categorized as monogamy or polygamy. The purpose of marriage is to create a stable household for raising offspring and reduce competition among individuals.
Step-by-step explanation:
Marriage can be defined as a legally recognized social contract between two people, traditionally based on a sexual relationship and implying a permanence of the union. It can vary across societies in terms of whether a legal union is required, whether more than two people can be involved, or whether it is a religious or civil union. Anthropologists classify marriage customs into monogamy (a union of two spouses) and polygamy (a union involving more than two spouses). The purpose of marriage is to provide a stable household for raising and nurturing offspring and to reduce competition among individuals.