Housing vacancy refers to a state in which dwellings remain unoccupied and unrented for an extended period. A distinction is made between frictional vacancy, which arises during tenant turnover, and structural vacancy, which indicates a permanent lack of demand. Structural vacancy is a serious problem particularly in rural areas and shrinking cities, threatening investment and property value retention. In German urban agglomerations, by contrast, vacancy is minimal. Municipalities use vacancy registers and subsidy programmes to bring abandoned buildings back into use. High vacancy rates can also have negative effects on the urban environment and social cohesion within affected communities.