Monogamy is an exclusive conjugal relationship between a man and a woman. Marriages in Western culture are set up based on the concept of monogamy. Polygamy, a "marriage" with multiple partners, occurred in ancient cultures, but has become less common over time.
In the Bible, Solomon had 700 wives and 300 concubines, but being from pagan lands, they tempted him to worship false gods, and this led to the dissolution of the holy Kingdom. By the time of Jesus and the writings of the New Testament, being "the husband of one wife" was a requirement for an elder. Monogamy can be found in the animal kingdom, even among pack animals. Wolves, for instance, mate for life in monogamous pairs.