As per the Ramsar Convention,
Wetlands are areas of marsh ,fen ,peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, Fresh, brackish or salt, including areas of marine water the depth of which at low tides does not exceed six metres.
Wetlands are land areas that are saturated or flooded with water either permanently or seasonally. Inland wetlands include marshes, ponds, lakes, fens, rivers, floodplains, and swamps. Coastal wetlands include saltwater marshes, estuaries, mangroves, lagoons and even coral reefs. Fish ponds, rice paddies, and salt pans are human-made wetlands.
The benefits provided by wetlands are called their “Ecosystem services”