A visa is a certificate of permission granted by government departments of a country to foreigners pursuant to national laws, allowing them to enter, leave, or to pass through that country.

According to principles of international law, all sovereign states have absolute discretion in deciding whether foreigners are permitted to enter and/or leave their territories. Sovereign states may grant via, reject the issuance of visa, or cancel those already granted pursuant to their national laws.

Visa is commonly attached to the passport or other certificates for international travel held by the applicant. In special circumstances, a visa may be issued separately against presentation of valid passports or other certificates for international travel. As technologies advance, some countries have started to issue electronic visa and biological visa, promising significantly improved anti-counterfeiting functions.

Other than facilitating the screening of people who enter or leave a country's territory, visa also contributes in other major aspects, safeguarding homeland security, keeping illegal immigrants and criminals out of the country, to just name a few.

A passport is a certificate of identification, whereas a visa is a certificate of permission granted by sovereign states to foreigners or their citizens, allowing them to enter, leave, or to pass through their territory.

Visas are normally attached to passports or other travel certificates, and sometimes it is issued separately. For instance, immigrant visas of the United States and Canada is issued on A4 papers. In Singapore, visas granted to foreigners are issued separately. Generally speaking, a visa is only valid when presented together with a passport.

There are six types of visa depending on entry and exit, namely, exit visa, entry visa, entry and exit visa, exit and entry visa, re-entry visa and transit visa. Bearers of exit visa may only exit the country; and if the bearer intends to enter the country, he/she must apply for an entry visa. As for a bearers of entry visa, exit visa must be applied if they intend to exit the country. Bearers of an entry and exit visa may leave the country or re-enter the country. Bearers of multiple entry and exit visa are allowed to enter and exit the country during the validity period of the visa.

According to the reason for entry and exit, visa can normally be divided into diplomatic visa, official visa, immigrant visa, non-immigrant visa, courtesy visa, tourist visa, work visa, student visa, business visa and family visa. In this regard, countries have varying rules.

According to the length of stay, visa can be divided into long-term visa and short-term visa. A long-term visa is issued to applicants whose stay in the destination country exceeds 3 months. Regardless of the purpose of the visit, application for a long-term visa generally requires a longer time period. A short-term visa is issued to applicants whose stay in the destination country is within 3 months, and the time required for its application is relatively short.

According to the number of entries, visa can be divided into single entry visa and multiple entry visa. 

According to the number of users, visa can be divided into individual visa and group visa.

Based on the convenience provided to the bearer, visa can be divided into separate visa, visa on arrival, etc.

Visas of most countries are divided into diplomatic visa, official (for government officials) visa and ordinary visa.

For the People's Republic of China, there are four types of visas, namely, diplomatic visa, courtesy visa, official visa and ordinary visa, which are issued to foreigners who apply for entry.

According to the purpose of entry, visa can be divided into immigrant visa and non-immigrant visa. Obtaining an immigrant visa indicates that the applicant has been granted with permanent residence in the destination country, and after a certain period of residence, he/she may become a legal citizen of that country. Non-immigrant visas can be divided into several categories, such as business, work, study, tourist, and medical.

Shandong QUSON offers popular visa services that cover over 100 countries, including family & friend visit visa, business visa, tourist visa, visitor's visa, electronic visa, study visa, etc. Our visa consultants will help you choose the most suitable visa type according to the purpose and length of your visit and your own needs, allowing you to visit family members, work, travel, or conduct business affairs in foreign countries. As countries may change their policies and fees on visa any time, we kindly advise you to contact us for more details on visa.