A person can be an Indian national in 4 ways. They are by birth, by descent, by registration and by naturalization
1. By Birth:
All the persons born in India on or after 26.01.1950 but before 01.07.1987 are Indian citizens irrespective of the nationality of their parents.
All the persons born in India between 01.07.1987 and 02.12.2004 are citizens of India provide either of their parents is a citizen of the country at the time of his/her birth.
All persons born in India on or after 3.12.2004 are citizens of India provided both of their parents are Indians or at least one parent is a citizen and the other is not an illegal migrant at the time of birth.
2. By Descent:
Any person born outside India on or after January 26, 1950, are citizens of India by descent if their father was a citizen of India by birth.
Any person born outside India on or after December 10, 1992, but before December 3, 2004, if either of their parents was a citizen of India by birth.
Any person born outside India on or after December 3, 2004, has to acquire citizenship provided his/her parents declare that the minor does not hold a passport of another country and his/her birth is registered at an Indian consulate within one year of birth.
3. By Registration:
Citizenship can also be acquired by registration. Some of the rules are:
A person of Indian origin who has been a resident of India for 7 years before applying for registration.
A person of Indian origin who is a resident of any country outside undivided India.
A person who is married to an Indian citizen and is ordinarily resident for 7 years before applying for registration.
Minor children of persons who are citizens of India.
A person can acquire citizenship by naturalization if he/she is ordinarily resident of India for 12 years (throughout 12 months preceding the date of application and 11 years in the aggregate) and fulfills all qualifications in the third schedule of the Citizenship Act which are given below. If he fulfills he has to declare that
(a) he is not a subject or citizen of any country where citizens of India are prevented by law or practice of that country from becoming subjects or citizens or that country by naturalization;
(b) If he is a citizen of any country, he has renounced the citizenship of that country in accordance with the law therein in force in that behalf and has notified such renunciation to the Central Government;
(c) he has either resided in India or been in the service of a Government in India or partly the one and partly the other, throughout the period of twelve months immediately preceding the date of the application;
(d) that during the 12 years immediately preceding the said period of twelve months, he has either resided in India or been in the service of a Government in India, or partly the one and partly the other, for periods amounting in the aggregate to not less than nine years
(e) he is of good character;
(f) t he has adequate knowledge of a language specified in the Eighth Schedule to the Constitution; and
(g) that in the event of a certificate of naturalization being granted to him, he intends to reside in India or to enter into or continue in, service under a Government in India or under an international organization of which India is a member or under a society, company or body of persons established in India: