1, definition: visa is a sovereign authority in national or foreign citizens passport or other travel document endorsement, sealing, to show up in and out of the country or pass the country, also can be said to be issued to them a proof of the type of visa.

2, visa classification: visa according to the nature of exit and entry is divided into: exit visas, entry visas, entry and exit visas, entry and exit visa, and re-entry visa and transit visa and so on six categories.

3, visa: the period of validity of visa is a very important content of the visa. Visa issued by the world all sovereign basically all show that the period of validity. There is no valid visa doesn't exist. Visa, that is to say the visa within a certain period of time, effectively over this period of time, the visa is invalid. So, for the applicant for the China visa, must be in after getting a visa, bear in mind that the validity of your visa, and in the period of validity of the destination.

4, visa periods: refer to permit visa winner for the duration of the stay.

5, visa valid number: refers to visa or stay within the time period allowed, can one, second, or more entry and exit