Secondary suites, or accessory dwelling units, ADUs, or in-law apartments, are self-contained apartments, cottages, or small residential units, that are located on a property that has a separate main, single-family home, duplex, or other residential unit. In some cases, the ADU or in-law is attached to the principal dwelling or is an entirely separate unit, located above a garage or in the backyard on the same property. In British English the term "annex" or granny annex is used instead. Reasons for wanting to add a secondary suite to a property may be to receive additional income, provide social and personal support to a family member, or obtain greater security.