If the university gives a student the admission to study the program applied for, the University will send the student a form I-20A-B, which is the legal form that denotes that the student is admitted and eligible for applying for a Visa. The immigration laws of the United States permit foreign students to come to the U.S. to attend school at many academic levels.
Basic requirements for student visa filing
More info about study in USA:
READY TO STUDY IN USA?