A visa is an official document issued by a country's government that allows a person to enter, stay, or leave that country for a specific purpose and duration. Visas can be required for various reasons, such as tourism, work, study, or family visits. Each country has its own visa policies, which may include different types of visas, application processes, and eligibility criteria. To obtain a visa, individuals typically need to submit an application along with supporting documents, such as a passport, photographs, and proof of travel plans. Some countries, like the United States or Canada, may also require an interview as part of the visa application process.