Feature in archaeology and especially excavation has several different but allied meanings. A feature is a collection of one or more contexts representing some human non-portable activity that generally has a vertical characteristic to it in relation to site stratigraphy. Examples of features are pits, walls, and ditches. General horizontal elements in the stratigraphic sequence, such as layers, dumps, or surfaces are not referred to as features. Examples of surfaces include yards, roads, and floors. Features are distinguished from artifacts in that they cannot be separated from their location without changing their form.