When most people think about the term "immigration" and the major points that this loaded word brings up, they probably think about a family that is just trying to cross the border and get U.S. citizenship. While this isn't necessarily wrong in some cases, there are many other immigration situations that arise, and most of these situations have layers and other intricacies inherent to them.
For example, not every visa that is handed out is "permanent" or grants an individual citizenship. There are shorter term visas, B-1 and B-2 visas, that give people some time to enter and stay in the United States. The B-1 visa is for tourists or people who are going to see friends or family in the United States. The B-2 visa, meanwhile, is for business purposes.
B-2 visa applicants must be going to the United States for a legitimate business, commercial or professional purpose. There are many other requirements for a B-2 visa applicant -- as well as for a B-1 visa applicant, so anyone who wants to obtain such a visa should consult with an attorney to ensure their application is being handled properly.
At the same time, you need to remember that there are state immigration laws in addition to the obvious federal immigration laws on the books. You need to be aware of how these state laws apply to you and your visa in addition to how the federal laws apply to you. All of this can be confusing at times; so again, if you are need of help, discuss things with an attorney that has experience with immigration law.
Source: FindLaw, "To B or Not to B: When B Non-immigrant Visas Are Appropriate," Accessed Dec. 30, 2014
Source: FindLaw, "Federal vs. State Immigration Laws," Accessed Dec. 30, 2014