Dual citizenship allows a person to be a citizen of more than one country. Many countries around the world allow dual citizenship. Others, however, require its citizens to renounce all citizenship of other nations. Other nations deny citizenship in order to control multiple citizenship.
Even in countries where dual citizenship is allowed, there may be some restrictions. For example, a person with dual citizenship may not be able to serve in the military or hold public office. Some nations allow dual citizenship under specific conditions.