Final answer:
Marriage is a socially recognized union that serves multiple functions, including creating alliances between individuals and families. It can be a union between a man and a woman, any two adults regardless of gender, or multiple spouses in polygamous societies.
Step-by-step explanation:
Marriage is the formation of a socially recognized union. Depending on the society, it may be a union between a man and a woman, between any two adults (regardless of their gender), or between multiple spouses in polygamous societies. Marriages are most commonly established to provide a formal structure in which to raise and nurture offspring (whether biological or adopted/fostered), but not all marriages involve reproduction, and marriage can serve multiple functions. One function is to create alliances between individuals, families, and sometimes larger social networks. These alliances may provide political and economic advantages. While there are variations of marriage, the institution itself, with a few notable exceptions, is universal across cultures.