Admission as an undergraduate student in most top public or private universities in Brazil requires that the applicant pass a competitive entrance examination known as Vestibular. Contrary to what happens in the United States, candidates must declare their intended university major when they register for the Vestibular. Although it is theoretically possible to switch majors afterwards (in a process known within the universities as "transferência interna"), that is actually quite rare in Brazil. Undergraduate curricula tend to be more rigid than in the United States and there is little room to take classes outside one's major.