They take many forms including marshes, estuaries, mudflats, mires, ponds, fens, pocosins, swamps, deltas, coral reefs, billabongs, lagoons, shallow seas, bogs, lakes, and floodplains.
There are also human-made wetlands such as fish and shrimp ponds, farm ponds, irrigated agricultural land, salt pans, reservoirs, gravel pits, sewage farms and canals.
There are many different ways of categorising wetlands, and numerous different types. Most large wetland areas are a unique mosaic of different wetland types. For example, within the The Kafue Flats are found grasslands, lagoons, marshes, swamps and reed beds.