India has two sets of people as (i) Citizens (ii) Aliens. Citizens are full members of Indian state. They enjoy all civil and political rights. Aliens do not enjoy all the civil and political rights.
Constitution deals with the citizenship Act of 1955 prescribes five ways of acquiring citizenship viz. birth, descent, registration, naturalization and incorporation of territory.
By Birth: The act amended in 1986 provides that a person is a citizen of India by birth (a) if he is born in India on or after 26, Jan, 1950 but before 1st July, 1987 (or) (b) if he is born in India on or after 1 July, 1987 but before 3rd December, 2004 is considered citizen of India by birth if either of his parents was a citizen of India. The second provision, added in 1986, makes the acquisition of Indian citizenship by the persons coming to India as refugees from Srilanka, Bangladesh and some African countries more difficult.
By Descent: Citizen of India by descent if at the time of his birth either of his parents was an Indian citizen. But before 1992, a person born outside India was entitled to Indian citizenship only if his father was an Indian citizen.
By Registration: Persons of Indian origin who are ordinarily resident in India for five years immediately before making an application for registration.
By naturalization: He has either resided in India or has been in Indian government service for 12 months before making an application for naturalization.
By incorporation of Territory: If any foreign territory becomes a part of India, the government of India specifies the persons who among the people of territory shall be citizens of India.
Loss of Citizenship: The citizenship Act 1955, prescribes three ways of losing citizenship whether acquired under the act or prior to it under the constitution, viz. renunciation, termination and deprivation.
Commonwealth Citizenship: The Citizenship Act 1955, recognizes formally the concept of Commonwealth Citizenship. Every person who is citizen of a Commonwealth country has the status of a Commonwealth Citizen in India.
Single Citizenship: Indian constitution is federal and envisages of dual polity (centre & state). It provides for only single citizenship, that is the Indian citizenship. The citizens in India owe allegiance only to the union. There is no separate state citizenship.