A visa is a notation stamped and signed on your passport showing the number of days and entries allowable for your trip. Apply for a student visa at the consulate nearest your home well in advance of your departure; the same is true if you require a business visa of longer than 30 days. One-year renewable student visas are available (sometimes with considerable red tape). An ordinary 180-day tourist card may be the easiest option, if you can manage it.