Social dance usually performed by couples in dance halls or at social gatherings. During the 20th century these dances came to be performed widely in competitions, which flourished in Britain and America following the First World War. In 1929 the Official Board of Ballroom Dancing was founded and by the 1930s standardization of training and levels of expertise had been established. Today the annual Open British Championship ranks as the world's most important competition. Standard ballroom dances include the waltz, Viennese waltz, foxtrot, tango, lindy, charleston, and the quickstep. Latin American dances such as the rumba, samba, paso doble, and cha-cha-cha are also part of the ballroom repertoire. Recent television programmes including the competition Strictly Come Dancing have contributed to a mass revival of interest.