The word wetland first appeared in Notice No.39 of the US Fish and Wildlife Service in 1956, which defined wetland as "land covered by intermittent or permanent shallow water."

1979, in order to classify the wetland and deep-water ecological environment in the United States, the Bureau redefined the meaning of wetland, and thought that "wetland is a transitional land between terrestrial ecosystem and aquatic ecosystem, and the water level of this land often exists or is close to the surface, or is covered by shallow water ...". 197 1 year, the Convention on Wetlands of International Importance Especially as Waterfowl Habitat (hereinafter referred to as "Wetlands Convention") was adopted in Ramsar. The Convention defines wetlands as: "Whether natural or artificial, permanent or temporary marshlands, wetlands, peatlands or waters, with static or flowing water bodies, or fresh water, brackish water or water.

China has accumulated rich experience in the study of swamps, beaches and other wetlands, and has formed a wetland classification system with China characteristics in practice. It is generally believed that "wetland refers to the area where shallow water accumulates or the soil is too wet all the year round in the ocean and inland."

Although the concept of wetland has not been unified at present, they have a common feature: from different angles, wetland is a special ecosystem, which is different from terrestrial ecosystem and aquatic ecosystem and is a transitional ecosystem between them.