Citizenship of the United States
A person who is considered a citizen by more than one nation has "dual citizenship". It is possible for a United States citizen to have dual citizenship; this can be achieved in various ways, such as by birth in the United States to a parent who is a citizen of a foreign country (or in certain circumstances the foreign nationality may be transmitted even by a grandparent) by birth in another country to a parent(s) who is/are a United States citizen/s, or by having parents who are citizens of different countries. Anyone who becomes a naturalized U.S. citizen is required to renounce any prior "allegiance" to other countries during the naturalization ceremony; however, this renunciation of allegiance renunciation of citizenship to those countries.
Identity documents in the United States
A child born abroad to two U.S. citizen parents, or one citizen parent and one non-citizen, also typically has citizenship from birth. Such births are registered with the nearest U.S. embassy or consulate. If the embassy or consulate determines the child acquired citizenship at birth, it issues a Consular Report of Birth Abroad, also known as Form FS-240. A birth certificate will also be issued locally in the country where the child was born. The consular report is proof of U.S. citizenship and may be used to obtain a passport for the child and register the child for school, among other purposes.