North Rhine-Westphalia or North-Rhine/Westphalia, commonly shortened to NRW, is a state (Land) in Western Germany. With more than 18 million inhabitants, it is the most populous state in Germany. Apart from the city-states, it is also the most densely populated state in Germany. Covering an area of 34,084 square kilometres (13,160 sq mi), it is the fourth-largest German state by size.

The Rhine-Ruhr metropolitan region is the largest metropolitan region in Germany, with over ten million inhabitants. A polycentric conurbation with several major urban concentrations, the region covers an area of 7,110 square kilometres (2,750 sq mi), entirely within the federal state of North Rhine-Westphalia. The Rhine-Ruhr metropolitan region spreads from the Ruhr area (Dortmund-Bochum-Essen-Duisburg) in the north to the urban areas of the cities of Mönchengladbach, Düsseldorf, Wuppertal, Leverkusen, Cologne, and Bonn in the south. The location of the Rhine-Ruhr at the heart of the European Blue Banana makes it well connected to other major European cities and metropolitan areas such as the Randstad, the Flemish Diamond and the Frankfurt Rhine Main Region.