A visa is a document which is issued to a foreign national who wishes to travel to the United States. There are different types of visas. Each category has their own set of rules and regulations. Specific visas exist for people wishing to attend university and different visas exist for people wishing to work or come as a tourist. Applications for visas are made in the foreign national's home country at the United States Embassy. There are several requirements for any type of visa; each person has to have enough money to support themselves during their stay in the country and a person must not have a criminal background.
Visas can be particularly hard to get for people from certain countries due to the fear that the person will stay in the country and work illegally. It is normal for the visa to have an expiration date of no more than one year, but most visas have the ability to be renewed. Normally, a person must show that they have a reason to return to their home country such as a job, family, or property ownership.