It can have various forms and functions in different cultures, serving in relative proportions as a social protection for, and control over, the widow and her children. She may have the right to require her late husband's extended family to provide her with a new man, or conversely she might have the obligation to accept the man put forward by the family, with no real prospect of turning him down, if her birth family will not accept her back into their home.
The custom is sometimes justified on the basis that it ensures that the wealth does not leave the patrilineal family. It is also sometimes justified as a protection for the widow and her children.
A form of widow inheritance existed in ancient Judaism, where it is known as levirate marriage (see yibbum). It is known in India. It is common in certain African groups, for example the Luo in Kenya and Uganda around Lake Victoria.
- Levirate marriage, the term by which this practice is better known