In archaeological excavation, a feature is a collection of one or more contexts representing some human non-portable activity, such as a hearth or wall. Features serve as an indication that the area in which they are found has been interfered with in the past, usually by humans. Features are distinguished from artifacts in that they cannot be separated from their location without changing their form. Artifacts are portable, while features are non-portable. Artifacts and features can both be made from any available material, with the primary distinction being portability.