A marriage of convenience is a marriage contracted for reasons other than that of love and commitment. Instead, such a marriage is entered into for personal gain, or some other sort of strategic purpose, such as a political marriage. There are some cases in which those married do not intend to live together as a couple, and typically got married only for one of them to gain the right to reside in a country, meaning a marriage of benefit.
A marriage of convenience that is neither a sham marriage entered into for fraudulent purposes nor a forced marriage, is not against the law.
In many cultures, it is usual for parents to decide their adult children's marriages; this is called an arranged marriage.
Source: Wikipedia