1 .Hindu by Religion : In this category two types of persons fall –
a)Those who are originally Hindus, Jains, Sikhs or Buddhist by religion, and
b) Those who are converts or reconverts to Hindu, Jain, Sikhs or Buddhist religion
c) Converts and Reconverts to Hinduism
2. Hindu by Birth : A child whose both the parents were Hindus, Sikhs, Jains or Buddhists at the time of his birth, is regarded as Hindu. A person will be Hindu if at the time of his birth one of the parents was Hindu and the child is brought up as a member of the tribe, community, group or family to which Hindu parent belonged at the time of his birth.
3. Who are not Muslims, Christians, Parsis or Jews : Any person who is not a Muslim, Christian, Parsi or Jew and who is not governed by any other law, is governed by Hindu law, unless it is proved that Hindu law is not applicable to such a person
Under the Codified Law : Section 2 of the Hindu Marriage Act 1955, provides that the Act applies to the persons listed below (and similar provisions are also made in the other enactments of Hindu Law) –
1. Application of Act – This Act applies –
a) to any person who is Hindu by religion in any of its forms of development, including a Virashaiva, a Lingayat or a follower of the Brahmo, Prarthana or Arya Samaj;
b) to any person who is a Buddhist, Jaina or Sikh by religion; and
c) to any other person domiciled in the territories to which this Act extends, who is not a Muslim, Christian, Parsi or Jew by religion, unless it is proved that any such person would not have been governed by the Hindu law or by any custom or usage as part of that law in respect of any of the matters dealt with herein if this Act had not been passed.