Hearths are common features of many eras going back to prehistoric campsites and may be either lined with a wide range of materials, such as stone or left unlined.
Occasionally site formation processes—e.g., farming or excavation—deform or disperse hearth features, making them difficult to identify without careful study.
Often present are fragmented fish and animal bones, carbonized shell, charcoal, ash, and other waste products, all embedded in a sequence of soil that has been deposited atop the hearth.
Although carbon dates can be negatively affected if the users of the hearth burned old wood or coal, the process is typically quite reliable.
In the Byzantine Empire a tax on hearths known as kapnikon was first explicitly mentioned for the reign of Nikephorus I (802–811) although its context implies that it was already then old and established, and perhaps it should be taken back to the 7th century AD.
Also exempt were charitable institutions such as schools and almshouses, and industrial hearths with the exception of smiths' forges and bakers' ovens.
[3] Hearth tax records are important to local historians as they provide an indication of the size of each assessed house at the time.
Roehampton University has an ongoing project which places hearth tax data in a national framework by providing a series of standard bands of wealth applicable to each county and city.