Alderney is the northernmost of the inhabited Channel Islands. It is part of the Bailiwick of Guernsey, a British Crown dependency. (Note: A bailiwick is typically the area of jurisdiction of a bailiff, and once also applied to territories in which a privately appointed bailiff exercised the sheriff's functions under a royal or imperial writ.)
The island's area is 3 square miles (8 km2), making it the third-largest island of the Channel Islands, and the second largest in the Bailiwick. It is around 10 miles (15 km) to the west of the La Hague on the Cotentin Peninsula, Normandy, in France, 20 miles (30 km) to the northeast of Guernsey and 60 miles (100 km) from the south coast of Great Britain. It is the closest of the Channel Islands to France and to the United Kingdom.