A midden (also kitchen midden or shell heap) is an old dump for domestic waste which may consist of animal bone, human excrement, botanical material, mollusc shells, potsherds, lithics (especially debitage), and other artifacts and ecofacts associated with past human occupation.

Middens are a type of archaeological feature, consisting of localized patches of dark-colored earth and concentrated artifacts which resulted from the deliberate discard of refuse, food remains, and domestic materials such as broken and exhausted tools and crockery.

Middens are composed of shells (oyster, clam, mussel) and faunal remains (mammal, fish, bird, and reptile bones and teeth). Botanical remains, primarily seeds, are also preserved in middens.

Midden deposits can contain a variety of archaeological material, including animal bone, feces, shell, botanical material, vermin, sherds (fragments of pottery), lithics (stone works and the chips or flakes of stone produced from carving, known as debitage), and other artifacts and ecofacts (natural objects not touched by humans, such as seeds, but carrying archaeological significance) associated with past human occupation.

"Midden" is the fancy name scientists use for piles of debris that packrats collect near their nests. These piles are made up of seeds, twigs, animal bones and other materials cemented together by urine.