In geography, a marsh, or morass, is a type of wetland which is subject to frequent or continuous flood. [1] Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, and other herbaceous plants. Woody plants will be low-growing shrubs. A marsh is different from a swamp, which has a greater proportion of open water surface and may be deeper than a marsh. In North America, the term "swamp" is used for wetland dominated by trees rather than grasses and low herbs.

The water of a marsh can be fresh (freshwater marsh), brackish (brackish marsh), or saline (salt marsh).