The I-20 form, officially known as the "Certificate of Eligibility for Nonimmigrant Student Status," is a crucial document issued by U.S. educational institutions to international students. It certifies that the student has been admitted to a full-time study program and has sufficient financial resources to stay in the U.S. The I-20 is essential for applying for an F-1 or M-1 student visa, entering the U.S., and maintaining student status while studying.