Border control is the implementation of border controls on travel between Svalbard, which maintains a policy of free migration as a result of the Svalbard Treaty (Norwegian: Svalbard-traktaten; ) and the Schengen Area, which includes the rest of Norway. The Kingdom of Denmark also maintains a complex system of subnational countries with autonomous customs policies, since they aren’t within the European Union like the Danish mainland. These are Greenland () and the Faroe Islands (). These areas do not maintain strict immigration controls with the Schengen Area, but border controls are sporadically enforced for customs purposes. Other examples of effective internal border
Country separate countries—the Faroe Islands, and Greenland—which are almost fully internally self-governing. The Kingdom of the Netherlands, a sovereign state, comprises four separate countries: Netherlands, Aruba, Curaçao, and Sint Maarten. Although not sovereign states, England, Scotland, Wales and Northern Ireland are countries (depending on context), which collectively form the United Kingdom—a sovereign state that is commonly, but erroneously referred to as a country. The United Kingdom is a Union of four separate countries brought about by a series of International treaties and legislated for by several Acts of Union, the first of which being the Acts of Union 1707 in both