In common historic and modern usage, a hearth is a brick- or stone-lined fireplace or oven used for cooking and/or heating. Because of its nature, in historic times the hearth was considered an integral part of a home, often its central or most important feature. This concept has been generalized to refer to a homeplace or household, as in the terms "hearth and home" and "keep the home fires burning."
In archaeology, a hearth is a firepit used by prehistoric peoples. Hearths are common features of prehistoric campsites, and may be either lined with rocks (or, very occasionally, some other material such as ivory or bone) or left unlined. Hearths were used for cooking, heating, and processing of some stone, wood, faunal, and floral resources. Occasionally, site formation processes deform or disperse hearth features, making them difficult to identify without careful study.
Lined hearths are easily identified by the presence of fire-cracked rock, often created when the heat from the fires inside the hearths chemically altered and cracked the stone. Often present are fragmented fish and animal bones, carbonized shell, charcoal, ash, and other waste products, all imbedded in a matrix of soil that has been deposited atop the hearth. Unlined hearths, which are less easily identified, may also include these materials. Because of the organic nature of most of these items, they can be used to pinpoint the date the hearth was last used via the process of radiocarbon dating. Although carbon dates can be negatively affected if the prehistoric users of the hearth burned old wood or coal, the process is typically quite reliable.