The visa issuing authority
The visa 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, especially for long-term visas; some countries deny such visas to persons with certain illnesses, such as AIDS. The exact conditions depend on the country and category of visa. Notable examples of countries requiring HIV tests of long-term residents are Russia and Uzbekistan. In Uzbekistan, however, the HIV test requirement is sometimes not strictly enforced. Other countries require a medical test that includes an HIV test, even for a short-term tourism visa. For example, Cuban citizens and international exchange students require such a test approved by a medical authority to enter Chilean territory.
The issuing authority may also require applicants to attest that they have no criminal convictions, or that they do not participate in certain activities (like prostitution or drug trafficking). Some countries will deny visas if travellers' passports show evidence of citizenship of, or travel to, a country that is considered hostile by that country. For example, some Arabic-oriented countries will not issue visas to nationals of Israel and those whose passports bear evidence of visiting Israel.
Visa Requrement
Many countries frequently demand strong evidence of intent to return to the home country, if the visa is for a temporary stay, due to potential unwanted illegal immigration. Proof of ties to the visa applicant's country of residence is often demanded to demonstrate a sufficient incentive to return. This can include things such as documented evidence of employment, bank statements, property ownership, and family ties.