Visas typically may include limits on the duration of the foreigner’s stay, areas within the country they may enter, the dates they may enter, the number of permitted visits, or an individual’s right to work in the country in question. Visas are associated with the request for permission to enter a territory and thus are, in most countries, distinct from actual formal permission for an alien to enter and remain in the country. In each instance, a visa is subject to entry permission by an immigration official at the time of actual entry and can be revoked at any time. A visa most commonly takes the form of a sticker endorsed in the applicant’s passport or other travel documents.
Visa applications in advance of arrival give countries a chance to consider the applicant’s circumstances, such as financial security, the reason for travel, and details of previous visits to the country. Visitors may also be required to undergo and pass security or health checks upon arrival at the port of entry. Some countries require that their citizens, as well as foreign travellers, obtain an “exit visa” to be allowed to leave the country.
Some visas can be granted on arrival or by prior application at the country’s embassy or consulate, or through a private visa service specialist. The issuing authority, usually a branch of the country’s foreign ministry or department (e.g. U.S. State Department), and typically consular affairs officers, may request appropriate documentation from the applicant. This may include proof that the applicant is able to support himself in the host country (lodging, food), proof that the person hosting the applicant in his or her home really exists and has sufficient room for hosting the applicant, proof that the applicant has obtained health and evacuation insurance, etc. Some countries ask for proof of health status also.