All persons born in the United States are citizens of the United States.
This is perhaps the only simple rule of US citizenship. One of the most complicated areas of US citizenship law involves the passage of citizenship to children born outside the US to one or more US citizen parents. While naturalized US citizens are treated like natural born citizens, which includes those who are deemed citizens even when born outside the US, in almost every respect, there is one important office that only natural born citizens can hold the presidency. Also, a person who is a citizen from birth cannot be denaturalized. The rules determining when such children are citizens are extremely detailed, and vary a great deal depending on when the child was born.