Flanders (Dutch:  Vlaanderen (help·info), French: Flandre) nowadays refers to the Dutch-speaking northern part of Belgium. It is one of the regions and communities of Belgium. Historically, the name referred to a region located in the north-western part of present-day Belgium and adjacent parts of France and the Netherlands. Both in the historical and the contemporary meaning, the demonym associated with Flanders is Fleming, while the corresponding adjective is Flemish. Brussels is the capital of Flanders, though not fully under its jurisdiction.

Over the course of history, the geographical territory that was called "Flanders" has varied. From around 1000 AD, Flanders historically meant to English-speaking peoples the land situated along the North Sea from the Strait of Dover to the Scheldt estuary with ill-defined southern borders. It came to refer specifically to the County of Flanders, lasting from 862 to 1795, whose territory was situated in the northwestern part of what is now Belgium (the Belgian provinces of West Flanders and East Flanders), with extensive portions in what is now northern France (French Flanders), and a small area that is now part of the Netherlands (Zeelandic Flanders). Through marriage, the County of Flanders was joined with most of the rest of the Low Countries around 1400 AD, and it lost its independence. Most of the county's territory became part of an independent Belgium in 1830, and during the 19th and 20th centuries, it became increasingly commonplace to refer to the entire Dutch-speaking and northern part of Belgium as "Flanders", including the Belgian parts of the Duchy of Brabant and Limburg. In the late 20th century, Belgium became a federal state in which the Dutch-speaking part was given autonomy as the Flemish Community (Dutch: Vlaamse Gemeenschap) and the Flemish Region (Dutch: Vlaams Gewest); these two entities were effectively merged, and Flanders now refers to the territory of the Flemish Community, which has partial jurisdiction over Brussels, its capital.