Citizenship of the United States is a legal status that entails Americans with specific rights, duties, and benefits in the United States. It serves as a foundation of fundamental rights derived from and protected by the Constitution and laws of the United States, such as freedom of expression, due process, the rights to vote (however, not all citizens have the right to vote in all federal elections, for example, those living in Puerto Rico), live and work in the United States, and to receive federal assistance. The implementation of citizenship requires attitudes including pledging allegiance to the United States and swearing an oath to support and defend the constitution thereof.