A student visa is unlike almost any other immigration status because it depends on something the student does not fully control: continuous enrollment in a specific program at a specific school. This article explains how F, M, and J status actually work, what the document in the passport does and does not do, and why the record in the government database matters more than the visa stamp. It walks through the enrollment requirements that keep status alive, the narrow work authorizations available and the far more common ways students lose status by working without them, and the practical difference between falling out of status and accruing unlawful presence. It explains reinstatement, the alternative of departure and reentry, and the two-year home residence requirement that catches exchange visitors by surprise. Worked examples follow three students through a dropped course, an unauthorized internship, and a program that ended early. The article closes with the habits that prevent nearly all of it.