Final answer:
Marriage is a socially recognized union that can take different forms and serve various functions. It creates alliances and can offer political and economic advantages. The institution of marriage is universal across cultures.
Step-by-step explanation:
Marriage is the formation of a socially recognized union. 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. One function of marriage is to create alliances between individuals, families, and social networks, which can provide political and economic advantages. While there are variations of marriage, the institution is universal across cultures.