The Netherlands, informally Holland, is a country located in Northwestern Europe with overseas territories in the Caribbean. It is the largest of four constituent countries of the Kingdom of the Netherlands (the others being Aruba, Curaçao and Sint Maarten). In Europe, the Netherlands consists of twelve provinces, and borders Germany to the east, Belgium to the south, with a North Sea coast-line to the north and west. It also shares maritime borders with both countries and with the United Kingdom in the North Sea. The Caribbean overseas territories—Bonaire, Sint Eustatius and Saba—became special municipalities of the country of the Netherlands in 2010. The country's official language is Dutch, with West Frisian as a secondary official language in the province of Friesland, and English and Papiamento as secondary official languages in the Caribbean Netherlands. Dutch Low Saxon and Limburgish are recognised regional languages (spoken in the east and southeast respectively), while Dutch Sign Language, Sinte Romani, and Yiddish are recognised non-territorial languages.The four largest cities in the Netherlands are Amsterdam, Rotterdam, The Hague and Utrecht. Amsterdam is the country's most populous city and nominal capital, while The Hague holds the seat of the States General, Cabinet and Supreme Court. The Port of Rotterdam is the busiest seaport in Europe. Amsterdam Airport Schiphol is the busiest airport in the Netherlands, and the third busiest in Europe. The country is a founding member of the European Union, Eurozone, G10, NATO, OECD, and WTO, as well as a part of the Schengen Area and the trilateral Benelux Union. It hosts several intergovernmental organisations and international courts, many of which are centred in The Hague, which is consequently dubbed 'the world's legal capital'.Netherlands literally means "lower countries" in reference to its low elevation and flat topography, with only about 50% of its land exceeding 1 m (3.3 ft) above sea level, and nearly 26% falling below sea level. Most of the areas below sea level, known as polders, are the result of land reclamation that began in the 14th century. Colloquially or informally the Netherlands is occasionally referred to by the pars pro toto Holland. In the Republican period, which began in 1588, the Netherlands entered a unique era of political, economic, and cultural greatness, ranked among the most powerful and influential in Europe and the world; this period is known as the Dutch Golden Age. During this time, its trading companies, the Dutch East India Company and the Dutch West India Company, established colonies and trading posts all over the world.With a population of 17.6 million people, all living within a total area of roughly 41,800 km2 (16,100 sq mi)—of which the land area is 33,500 km2 (12,900 sq mi)—the Netherlands is the 16th most densely populated country in the world and the second-most densely populated country in the European Union, with a density of 526 people per square kilometre (1,360 people/sq mi). Nevertheless, it is the world's second-largest exporter of food and agricultural products by value, owing to its fertile soil, mild climate, intensive agriculture, and inventiveness.The Netherlands has been a parliamentary constitutional monarchy with a unitary structure since 1848. The country has a tradition of pillarisation and a long record of social tolerance, having legalised abortion, prostitution and human euthanasia, along with maintaining a liberal drug policy. The Netherlands abolished the death penalty in Civil Law in 1870, though it was not completely removed until a new constitution was approved in 1983. The Netherlands allowed women's suffrage in 1919, before becoming the world's first country to legalise same-sex marriage in 2001. Its mixed-market advanced economy had the eleventh-highest per capita income globally. The Netherlands ranks among the highest in international indices of press freedom, economic freedom, human development and quality of life, as well as happiness. In 2020, it ranked eighth on the human development index and fifth on the 2021 World Happiness Index.