An alien is an individual within the borders of the United States, who is not a citizen of the country. Aliens can be legal or illegal, and are also referred to as foreign nationals. Legal aliens are those who have entered the country legally, and are allowed to stay in the country legally as well. This involves having the proper documentation (such as a passport and valid visa) when coming into and staying in the country.

The Department of Homeland Security assigns an alien registration number to all legal aliens on arrival. This is a unique number that identifies the alien. Legal aliens can permanently reside within the country, or can be temporary such as tourists.

Illegal aliens are those who gain entry into and reside in the country without following the correct procedures or obtaining the required legal permission to do so. This includes illegally crossing the border or extending one’s stay past the time allocated to legally stay in the country.

Whether legal or illegal, aliens have some constitutional rights such as the right to due process and free speech. However, these rights are limited; some of the constitutional rights that may not apply to an alien include the right to vote, the right to bear arms or the right to hold certain offices especially in the civil service.

Illegal aliens have far more restrictions regarding the constitutional rights they have a right to. With the recent political climate in the country, they are also constantly at risk of deportation.