Usually a gathering of representatives of the three estates of a realm: the Church; the nobility; and the commons (representatives of the corporations of towns). They met to advise a sovereign on matters of policy. The name was applied to the representative body of the United Provinces of the Netherlands in their struggle for independence from Spain in the 16th century.

In France, it began as an occasional advisory body, usually summoned to register specific support for controversial royal policy. It was developed by Philip IV, who held a meeting in 1302 to enlist support during a quarrel with the pope. Initially summoned quite frequently, it never established itself as a regular institution and its powers to grant taxation were eroded in the late 14th and 15th centuries. Thereafter it tended to be summoned only at times of crisis, most notably in 1789, when the meeting of the States–General—the first since 1614—marked the start of the French Revolution.