Civics and English are the two subjects in which the person who is applying for Naturalized US citizenship is tested upon. The person must be a legitimate permanent dweller of America. The person who is applying for the citizenship must be of good moral character.
If the person has any criminal record or faced any criminal charge or proved to be disloyal to the Us Government, he has to meet with a solicitor. Then he has to complete the filling of Form N 400.
The potential candidate is tested on basic reading, writing and speaking in English. He must also be aware of the US History and government. Finally he had to take oath and show his allegiance to the adopted country.