Certificate issued or a stamp marked (on the applicant's passport) by the immigration authorities of a country to indicate that the applicant's credentials have been verified and he or she has been granted permission to enter the country for a temporary stay within a specified period. This permission, however, is provisional and subject to the approval of the immigration officer at the entry point. The common types of visas include: (1) Single entry visa: valid only for one visit. (2) Multiple entry visa: allows any number of visits within its validity period.