If not a U.S. citizen, every person who enters the U.S. has either an immigrant or nonimmigrant status.
This status is for people who enter the U.S. on a temporary basis – whether for tourism, business, temporary work, or study. Once a person has entered the U.S. in nonimmigrant status, they are restricted to the activity or reason for which they were allowed entry. Some people may have more than one visa in their passport, but they can only be admitted into the U.S. in one type of nonimmigrant status at a time. Most nonimmigrant visas are issued only to applicants who can demonstrate their intentions to return to their home country.
If a visa officer at a U.S. consulate abroad believes that an application for a nonimmigrant visa is only a pretext for an intent to stay permanently once allowed into the U.S., the officer may deny the visa application. The consular officer may conclude that the nonimmigrant does not have the intent to stay temporarily because s/he cannot show significant family or employment related ties to their country of origin.
This is for people who live permanently in the United States. Synonymous terms for immigrant status are: Permanent Resident, immigrant, green card holder, and resident alien. Gaining immigrant status can be a lengthy and complex process that requires close consultation with an immigration attorney.
Individuals who intend to apply for a "green card" may not be eligible for nonimmigrant status. Their nonimmigrant visa application may be denied if they appear to have the "dual intention" of coming to the U.S. temporarily while pursuing permanent resident status. Presently, only E, H-1, and L nonimmigrant categories are allowed to enter and remain nonimmigrants while simultaneously pursuing permanent resident status.
If it is your intention to temporarily visit the U.S. as a nonimmigrant student, scholar, or other category, be aware that the success of your visa application resides in your ability to demonstrate sufficient ties to your home country in addition to the requirements of whichever visa category to which you are applying. During your visa interview, you may be asked how your visit to the U.S. fits into your long range plans.
If you are interested in seeking immigrant status, do your research and talk to an immigration attorney about the options before taking any steps in the application process. If you are a student or scholar at UC Berkeley, speak to a BIO adviser about the implications of an application on your student or scholar status.