What do you mean by green card, passport and visa?

Visa is the annotation and seal of the sovereign organ of a country on the passport or other travel documents held by its own or foreign citizens to show that they are allowed to enter or leave the country or pass through it. It can also be said that it is an endorsement certificate issued to them. Generally speaking, a visa is a document issued by a country's entry-exit administration (such as immigration bureau or its embassy or consulate abroad) to approve the entry of foreign citizens. Passport is a legal document issued by a country to prove the nationality and identity of its citizens when they enter and leave the country and travel or stay abroad. The word passport means port pass in English. In other words, a passport is a passport for citizens to pass through international ports in various countries. Therefore, some countries in the world usually issue passes instead of passports. A green card is a permanent residence permit for foreign citizens. Holding a green card means that the cardholder has the permanent residence in the issuing country, and at the same time, holding a green card can exempt entry visas for a certain period of time. The term "green card" originated in the United States, because the earliest permanent residence permit in the United States was a green card. With the change of design, the version of 19 was updated. Now it is a white plastic card with a yellow-green pattern, but the name "green card" has been retained. Other countries follow the United States and call their permanent residence permits green cards.