Wetland" is a generic term for all the different kinds of wet habitats--implying that it is land that is wet for some period of time, but not necessarily permanently wet. Wetlands have numerous definitions and classifications in the United States as a result of their diversity, the need for their inventory, and the regulation of their uses. This article provides an overview of wetland definitions and classification systems of major wetland types in the United States. It also introduces the U.S. Fish and Wildlife Service (FWS) classification system (Cowardin and others, 1979) that is used throughout this volume.
Wetlands typically occur in topographic settings where surface water collects and (or) ground water discharges, making the area wet for extended periods of time. Examples of some of these topographic settings, and some common names for wetland types associated with them are: