Other dances sometimes placed under the umbrella "ballroom dance" include nightclub dances such as Lindy Hop, West Coast swing, nightclub two step, hustle, salsa, and merengue. The categorization of dances as "ballroom dances" has always been fluid, with new dances or folk dances being added to or removed from the ballroom repertoire from time to time, so no list of subcategories or dances is any more than a description of current practices. There are other dances historically accepted as ballroom dances, and are revived via the vintage dance movement.