In the context of international travel, what are visas?

Visas are official documents issued by a country's government that allow individuals to enter, stay, or exit that country for a specified period and purpose. They are essential for international travel, as they serve to regulate who can enter a nation and under what conditions. Each country has its own visa policies, which could include various types of visas—such as tourist, student, or work visas—tailored to the purpose of the visit.

The other options describe different concepts related to international travel but do not define what visas are. Temporary jobs in foreign countries fall under work opportunities and do not relate to the movement of travelers. Public transits refer to transportation services available to visitors, while insurance packages provide coverage for travelers against potential risks during their journey. Therefore, the most accurate representation of what visas are is the description of them as official documents that grant permission for entry into a country.