B-1 visa: Visitor for Business:
The alien may engage in commercial transactions not involving gainful employment, such as negotiating contracts, litigation, recognition of foreign judgments, consulting with clients or business associates. He or she may also participate in scientific educational, professional, religious, or business meeting. He or she may receive no salary or remuneration other than payment of expenses incidental to his or her temporary stay.
B-2 visa: Visitor for Pleasure:
This category permits entry for tourism, social visits to friends or relatives, health purposes, social conventions, participation in amateur musical or sporting events with no remuneration.
F Visa for Students and Trainees
The applicant must have a foreign residence which he or she has no intention of abandoning, be a bona fide student qualified to pursue a full course of study, and seek to enter the United States temporarily solely for the purpose of studying at a recognized school. The applicant may study only at the school he or she designates and which has been approved. The applicant must have available sufficient funds and outside financial support to ensure he or she will not become a public charge or accept unauthorized employment. He or she must be proficient in English or receive training to make him or her proficient, intend to depart the United States at the conclusion of his or her studies, and be qualified to attend the particular institution.
All students are given permission to be in the United States for “duration of status,” that is for the period of time needed to complete the educational program plus 60 days. If a student does not leave the U.S. by the end of the 60 days, he or she may be charged with criminal contempt.
At the end of the course of study a period of work authorization may be requested for the purpose of gaining experience in the field of study, known as “practical training.” If qualified, the student may also change non-immigrant status to a temporary non-immigrant work visa or adjust status to a permanent resident visa.