The Netherlands, officially Kingdom of the Netherlands, colloquially also referred to as Holland, is a country that lies at the western end of the North European Plain. Along with Belgium and Luxembourg it comprises the “Low Countries” (not an official name) or “Benelux” (an acronym for an economic liaison, now largely superseded by the European Union). The country is bordered on the south by Belgium, on the east by Germany, and on the north and west by the North Sea. Except for the southeastern part, the Netherlands is flat and about 40% of the country lies below sea level. The inhabitants of the Netherlands, called the Dutch, have built dikes to hold back the sea. The country is situated at the estuaries of the river Rhine, which originates in Switzerland, and the river Meuse, which runs via Belgium from France to the city of Rotterdam, the main seaport of the Netherlands.