An oast, oast house or hop kiln is a building designed for kilning (drying) hops as part of the brewing process. They can be found in most hop-growing areas and are often good examples of vernacular architecture. Many redundant oasts have been converted into houses. The names oast and oast house are used interchangeably in Kent and Sussex. In Surrey, Hampshire, Herefordshire and Worcestershire they are called hop kilns.