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.
Visa requirements for German citizens
Israel, subject to the Arab League boycott, does not stamp passports anymore. Instead, it issues ID cards to visitors. Previously, it was possible to get the stamp on a separate piece of paper. Kuwait, Lebanon, Libya, Saudi Arabia, Sudan, Syria and Yemen do not allow entry to people with evidence of travel to Israel, or whose passports have either a used or an unused Israeli visa.However, similar conflicts exist between other countries. Visitors with passport stamp of such countries may have trouble to enter the other countries. Germany allows its citizens to hold several German passports (two or three, in extreme cases up to ten) to circumvent such travel restrictions. However, these additional passports are valid only for a maximum of six years, even if the "main passport" is valid for ten years. Holding a German passport and a foreign passport at the same time, that is, dual citizenship, is restricted under the current German nationality law. Germany allows dual citizenship with other EU countries and Switzerland; dual citizenship with other countries is possible with special permission or if obtained at birth. Dual citizenship is also routinely granted when the other citizenship cannot be renounced or renunciation would be practically impossible.