A toilet seat is a hinged unit consisting of a round or oval open seat, and usually a lid, which is bolted onto the bowl of a toilet used in a sitting position (as opposed to a squat toilet). The seat can be either for a flush toilet or a dry toilet. A toilet seat consists of the seat itself, which may be contoured for the user to sit on, and the lid, which covers the toilet when it is not in use – the lid may be absent in some cases, particularly in public restrooms.