Sometimes I've been known as a rectangle that is defined as a quadrilateral polygon in which all four angles are right angles.

You may have seen me in such places as a wetland that features permanent inundation of large areas of land by shallow bodies of water, generally with a substantial number of hummocks, or dry-land protrusions. Swamps usually are regarded as including a large amount of woody vegetation. When a wetland area does not, it is usually termed a marsh.