A garage apartment is an apartment built within the walls of, or on top of, the garage of a house. The garage may be attached or a separate building from the main house, but will have a separate entrance and may or may not have a communicating door to the main house. A garage apartment is one type of "accessory dwelling unit" or ADU, a term used by architects, urban planners and in zoning ordinances to identify apartments smaller than the main dwelling on one lot or parcel of land. Other examples of ADU's include granny flats, English basements, mother-in-law suites, and auxiliary units.