Your visa is a sticker or stamp in your passport. It was given to you at an embassy or consulate, most likely in your home country. Your visa does not determine how long you can stay in the U.S. A visa is merely an entry ticket into the country. Depending on the type of visa you have, it means that you can enter and possibly re-enter the U.S. up until the expiration date. It does not legally determine if you can stay in the country -- it only lets you in. In other words, if your visa expires in 2018 but you are done with school in May 2017, you must leave by July 2017 (see 60 day voluntary departure). It does not mean you can stay until 2018 just because your visa says so. On the other hand, if your visa expired July 2016, but you are not done with school, that’s fine. You can stay in the country and continue schooling, as long as you are staying “in status” the entire time. You cannot leave the country and re-enter, though, on this visa. If you leave the U.S. then you must obtain a new visa to reenter the U.S.