Ports originally refer to coastal ports designated by the state for foreign trade. But now, the port is not only a commercial port for economic and trade exchanges (that is, trade), but also a port for politics, diplomacy, science and technology, culture, tourism and immigration. Ports not only refer to ports located along the coast. With the development of land and air transportation, foreign trade goods, entry-exit personnel and their luggage, mail and parcels can reach the hinterland of a country directly by railway and air. Therefore, the country has also set up ports to carry out foreign trade and border trade places such as international combined transport and international air parcel exchange.

Simply put, the port is the gateway designated by the state for foreign exchanges and the hub of international cargo transportation. To some extent, it is a special international logistics node. Therefore, the state formulates policies on foreign trade, politics, diplomacy, science and technology, cultural tourism and port immigration, allowing people, goods and vehicles to enter and leave the ports, airports, stations and passages of foreign countries (borders).