Île-de-France is a historical and administrative region of France. This region of France is heavily populated. Alone, it accounts for 18.8 % of the population of mainland France, making it the most populous region, with a population of nearly 12 million inhabitants, and the highest density of France. The territory of the Île-de-France is 12 011 km². The official language is French. Île-de-France is a major European hub for trade, it is the second European region in terms of gross domestic product.