Brussels, officially the Brussels-Capital Region, is a region of Belgium comprising 19 municipalities, including the City of Brussels, which is the capital of Belgium. The Brussels-Capital Region is located in the central portion of the country and is a part of both the French Community of Belgium and the Flemish Community, but is separate from the Flemish Region and the Walloon Region, located less than 4 kilometres (2.5 mi) to the south. Historically Dutch-speaking, Brussels saw a language shift to French from the late 19th century. Nowadays, the Brussels-Capital Region is officially bilingual in French and Dutch, although French is the majority language and lingua franca. Brussels is also increasingly becoming multilingual. English is spoken widely and many migrants and expatriates speak other languages as well.

French is a Romance language of the Indo-European family. It descended from the Vulgar Latin of the Roman Empire, as did all Romance languages. French evolved from Gallo-Romance, the Latin spoken in Gaul, and more specifically in Northern Gaul. Its closest relatives are the other langues d'oïl—languages historically spoken in northern France and in southern Belgium, which French (Francien) largely supplanted. French was also influenced by native Celtic languages of Northern Roman Gaul like Gallia Belgica and by the (Germanic) Frankish language of the post-Roman Frankish invaders. Today, owing to the French colonial empire, there are numerous French-based creole languages, most notably Haitian Creole. A French-speaking person or nation may be referred to as Francophone in both English and French.