Homeowner and rental vacancy rates are important measures of the health of housing markets, providing an indicator of the availability of housing relative to the demand for housing. In a well-functioning housing market, some number of vacancies is required for homebuyers and potential tenants to be able to find a home that suits their needs and preferences. Vacancy rates measure the number of vacant-for-sale or vacant-for-rent units relative to all homes in a housing market, representing a portion of the available supply of housing. Like housing prices and rents, vacancy rates are a function of the total supply and demand for housing in a market. Low vacancy rates indicate that housing supply is less than the housing demanded and are a symptom of a housing shortage. Since the Great Recession, vacancy rates nationally have declined, reaching recent lows following the COVID-19 pandemic in 2020.