A visa system is a set of regulations and processes that countries use to control the entry of foreign nationals. It typically involves the issuance of a visa, which is an official document allowing a person to enter, stay, or leave a country for a specific purpose, such as tourism, work, or study. Each country has its own visa requirements, which can vary based on the applicant's nationality and the intended duration of stay. Visa systems help governments manage immigration and ensure national security. They often require applicants to provide personal information, proof of financial stability, and sometimes a background check. Common types of visas include tourist visas, student visas, and work visas, each designed for different purposes and durations of stay.