The Low Countries are so called because much of their land along the North Sea coast and for some distance inland is either below sea level or just slightly above it. More than a quarter of the total land area of The Netherlands is below sea level, for instance. Natural sand dunes and a system of man-made sea walls and dikes protect the polders (artificially drained flat country largely below sea level) from flooding. The Prince Alexander Polder north of Rotterdam is the lowest point in the Low Countries and lies 22 feet (6.7 m) below sea level. The principal rivers of the Low Countries include the Schelde, Meuse (Maas), and branches of the lower Rhine. An extensive network of shipping canals and waterways links the major rivers. More than 3,000 square miles (8,000 square km) of fertile farmland have been reclaimed from the deltas of the Schelde, Meuse, and Rhine rivers and from the Zuiderzee, which was formerly a shallow arm of the North Sea cutting deep into the northwestern coast of The Netherlands.

Ethnically, the Low Countries form a transitional zone between the ancient Germanic and Latin heritages of western Europe. Dutch (Dutch language) (a Germanic language) is spoken in The Netherlands and in northern Belgium (where it is known as Flemish), while French (French language) (a Romance language) and its Walloon dialects are spoken in southern Belgium. In Luxembourg, Letzenburgish, a German dialect, is the spoken language of the majority. Most of the population of Belgium and Luxembourg is Roman Catholic, while religious adherence in The Netherlands is equally divided between Roman Catholics and Protestants.

The population density of the Low Countries is among the highest in Europe and in the world. All three countries are highly urbanized, and some nine-tenths of the region's total population resides in cities or urbanized communities. Brussels and Antwerp (in Belgium) and Amsterdam, Rotterdam, and The Hague (in The Netherlands) are among Europe's major cities.

The Low Countries are one of the world's more highly industrialized regions and have market economies that are heavily dependent upon external trade. In order to help secure and protect their trade, they were early pioneers in economic integration, forming the Belgium-Luxembourg Economic Union (BLEU) in 1921, followed after World II by Benelux. That union allows for the free movement of people, goods, capital, and services between the three countries; coordinates their policy in economic, financial, and social fields; and pursues a common foreign-trade policy. In 1958 the three nations of the Low Countries were among the six founding members of the European Economic Community (EEC; now in the European Union).

Conquered by the Romans in the 1st century BC, the Low Countries remained under Roman occupation until the early 5th century AD, when the area came under the control of the Franks. After the collapse of the Frankish Carolingian empire in the mid-9th century, a number of political units emerged in the area of the Low Countries, including the county of Flanders, the duchy of Brabant, the county of Holland, and the bishopric of Liège. The rule of the dukes of Burgundy and then of the house of Habsburg during the 15th and early 16th centuries brought a degree of unity and stability to the area. A revolt began against the rule of Spanish Habsburgs in 1568, and the predominantly Protestant northern provinces formed a Dutch republic, the United Provinces, 12 years later. Spain formally recognized Dutch independence in 1648. Throughout the 17th century the United Provinces was one of the great commercial powers of Europe.

The Low Countries came under the rule of revolutionary France in 1795, and in 1814 they were reunited as the independent Kingdom of The Netherlands. But the mostly Catholic southern provinces, which had remained under Habsburg rule during the 17th and 18th centuries (to 1795), revolted against the north and formed the independent kingdom of Belgium in 1831. Luxembourg, for much of its history a principality of the Holy Roman Empire, was set up as a grand duchy in 1815 to be ruled as a separate state by the kings of The Netherlands. That union ended in 1890.

During World War I The Netherlands remained neutral, while Belgium and Luxembourg were occupied by German forces. All the Low Countries were overrun by the Germans in World War II. After the war, all three countries abandoned their policies of neutrality and became founding members of NATO, proceeding from there to the customs union that became the expanded Benelux Economic Union in 1960. The Low Countries are constitutional and hereditary monarchies with parliamentary forms of government.