(I) By birth, (ii) By marriage (iii) By registration (iv) By naturalization and (v) By honorary conferment (vi) Dual citizenship (vii) Citizenship by descent (viii) Citizenship by adoption (ix) through conquest or wars.
Citizenship by Birth:
This is a situation when an individual is born in a country or to parents who are citizens of that country. Citizenship by birth is acquired naturally.
Citizenship by birth can be acquired by the law of blood or by the law of the place. By the law of blood, one automatically acquires the citizenship of the state where one’s parents are also citizens, whether or not the person was born within the territorial jurisdiction of that state.
For instance, someone born to Nigerian parents is automatically a Nigerian whether the person was born in America, Britain or Germany.
By the law of place, one automatically acquires the citizenship of the same state where lie/she was born without regard to the nationality of his/her parents.
For instance, someone can acquire citizenship of a state if he/she is born in that state whether or not his/her parents or grandparents are citizens of that state. A person born in America automatically becomes a citizen whether his/ her parents are indigenes or not.
Citizenship by marriage:
This type of citizenship is mostly acquired by women. When a woman is married to a man of a different state/ country, that woman automatically becomes a citizen of the husband’s state/country.
For instance, when a Nigerian male citizen marries an American female citizen, automatically the married American female citizen becomes a Nigerian citizen.
Citizenship by Registration:
This is the type of citizenship obtained by registering the birth of a child with the appropriate authority or in accordance with the laid down laws of the country where the child is born and where the parents reside.
After registration, the child automatically becomes a citizen of that country.
Citizenship by Naturalization:
This is the type of citizenship mainly acquired by foreigners who may voluntarily opt out of membership of one state into the membership of another state if they so desire and are able to satisfy certain conditions prescribed by that state.
Citizenship by naturalization can be acquired when an alien consciously applies to the president of the state or country where he lives to be recognized as a citizen while promising to renounce the citizenship of his own state and to comply with the legal system of the new state.
This type of citizenship can be acquired through the president granting a Certificate of Naturalization, which confers on the alien, full citizenship rights.
Citizenship by Honorary Conferment:
This is the type of citizenship conferred to an alien by another country probably because the recipient has distinguished himself in a manner commendable to the awarding country.
This type of citizenship is conferred to an individual as a mark of honour e.g. Nelson Mandela of South Africa was conferred with this honorary citizenship by the government of Brazil following his undaunted courage and determination to free his people from the apartheid regime while in prison.
Citizenship by adoption:
If a family living in a country decides to adopt from another country through legal process, it is a one way of acquiring citizenship.
Dual Citizenship:
It is legitimately possible for a person to hold citizenship of two countries. for example, a child born to Nigerian parents living in America becomes a U.S. citizen. the baby is also a Nigerian because the parents are Nigerians.
Citizenship by descent:
The is when grandparents claimed to have migrated from somewhere.
Citizenship through conquest or wars:
Another way of acquiring citizenship is through conquest or wars and by bringing under control those people conquered.