A visa is an official document that allows a person to enter, stay, or leave a country for a specific purpose, such as tourism, work, or study. It is usually stamped or attached to a person's passport, which is their identification for international travel. Different countries have different visa requirements, and the type of visa needed can vary based on the traveler's nationality and the purpose of their visit. To obtain a visa, travelers often need to apply through the embassy or consulate of the country they wish to visit. This process may involve filling out forms, providing documents like passports, and sometimes attending an interview. It's important to check the specific requirements for each country, as they can change frequently.