Explanation:

Constitution of India did not codify permanent laws for citizenship and put this onus on parliament. Using the powers of article 10 and 11, the parliament enacted Citizenship Act 1955 which has been amended from time to time. This act mentions four ways in which a person may be Indian citizen viz. by birth, by descent, by registration and by naturalization. Citizenship by birth and descent are called natural citizens.  Summary of these provisions are as follows: Citizenship by Birth
         Every person born in India on or after Jan 26, 1950 is a citizen of India provided his / her father is not an enemy alien or representative of a diplomatic mission. Citizenship by Descent
        A person born outside India on or after Jan 26, 1950 shall be a citizen of India by descent if his father or mother is a citizen of India at the time of his birth; provided such birth is registered in any of Indian consulates.
        Citizenship by Registration
        A person can acquire citizenship by registering themselves with prescribed authority. Such categories of persons are:
         Persons of Indian origin residing outside the territories of undivided India
        Those persons of Indian origin who are ordinarily residents in India and have been so resident for 6 months immediately before making application for registration
        Women who are married to citizens of India Children of Indian citizens
        Adult citizens of commonwealth country or republic of Ireland
        Citizenship by Naturalization
        A foreign citizen not covered by any of the above methods can get Indian citizenship on application of Naturalisation to the Government of India; with the following conditions
        Belongs to a country where the citizens of India are allowed to become subjects or citizens of that country by naturalization.
        Renounces the citizenship of his country and intimated the renunciation to the Government of India.
        Has been residing in India or serving the government for 12 months before the date of making application for naturalization.
        Possess a good character
        Posses working knowledge of Indian Languages Intends to reside in India after naturalization.
        Further, Government of India can waive any or all of the above conditions in case of a person who has rendered distinguished service in the cause of Philosophy, science, literature, arts, world peace etc. Citizenship by incorporating a new territory
        If a new territory becomes a part of India, the government of India specifies the persons of that territory who shall be citizens of India. Commonwealth Citizenship
        Every person who is born in commonwealth country, by virtue of that citizenship enjoys the status of Commonwealth Citizenship in India. The act empowers the government of India to make provisions of reciprocity for the enforcement of all or any rights of Citizens of India on citizens of commonwealth countries.