A marriage in which either the girl is below 18 years of age, or the boy is below 21 years of age, is a child marriage in India.
The essential condition for the validity of an Indian marriage is solemnization or conduct of the religious ceremonies prescribed by the religion to which the parties belong.
Child marriage is prohibited in India but such a marriage is not held as unlawful as of now by the courts. The Prohibition of Child Marriage Act, 2006 (PCMA) is the key law that puts some restraints on child marriages.