The I-20 is a document issued by U.S. educational institutions to international students. It certifies that a student has been accepted into a program and is eligible for a F-1 or M-1 visa. The I-20 includes important information such as the student's program of study, start date, and financial support details. To obtain an I-20, students must provide proof of acceptance and demonstrate sufficient funds to cover tuition and living expenses. Once issued, the I-20 is essential for applying for a student visa and must be presented at the U.S. port of entry upon arrival.