Visas are the official endorsement on a document required to secure an alien's admission to a country. A document such as a passport is one example. There are two types of visas that currently exist, one is a nonimmigrant and one is an immigrant. An immigrant visa allows a person to live in the United States permanently and ultimately work towards citizenship. A nonimmigrant visa may vary in duration as it simply allows an individual to be in the country on a temporary basis, this can be as simple as a short visit or the necessary duration for a job or education. There are a limited number of both types of visas given out each year by the government.