There are a couple ways to get status to be in America if you aren't a citizen. It can be something like a temporary status, parole, or something along those lines, it could be a family based adjustment of status, or it could be an employment based status.
The largest category of employment status is H1B. These are the people who are intelligent, specialized in skill, and have a company who is supporting their visa process because there aren't enough American workers who are skilled in the field and in the location to fill the position.
The Washington Post has printed a great article about a band created by a few H1B non-immigrants who are working in the computer field.
"H1Bees," an album recorded in a Gaithersburg basement-turned-studio, will be released today, its music a mix of Indian and Western beats with lyrics exploring the high-tech immigrant's experience in the United States. The troupe remains unnamed, giving composer Srikanth Devarajan top billing and referring to the remaining artists as "playback singers," which is customary on many Indian albums.
The cool thing is that they say this album wouldn't have been possible to make in India.