In some areas, child marriages and polygamy may occur in spite of national laws against the practice.
Since the late twentieth century, major social changes in Western countries have led to changes in the demographics of marriage, with the age of first marriage increasing, fewer people marrying, and more couples choosing to cohabit rather than marry.
Whom they marry may be influenced by socially determined rules of incest, prescriptive marriage rules, parental choice and individual desire.
In some areas of the world, arranged marriage, child marriage, polygamy, and sometimes forced marriage, may be practiced as a cultural tradition.
In some cultures, marriage is recommended or considered to be compulsory before pursuing any sexual activity.