A visa (short for the Latin carta visa, lit. "a document that has been seen") is a document issued by a country giving an individual permission to formally request entrance to the country during a given period of time and for certain purposes (see below for caveats and exceptions) and usually stamped or glued inside of a passport, or sometimes issued as separate pieces of paper.Many countries require possession of a valid passport and visa as a condition of entry for foreigners, though there exist exemptions (see below for examples of such schemes).Visas are associated with the request for permission to enter (or exit) a country, and are thus, for some countries, distinct from actual formal permission for an alien to enter and remain in the country.Some countries require that their citizens, and sometimes foreign travelers, obtain an exit visa in order to be allowed to leave the country.Until 2004, foreign students in Russia were issued only an entry visa on being accepted to University there, and had to obtain an exit visa to return home. This policy has since been changed, and foreign students are now issued multiple entry (and exit) visas.