An American negro music, originating in the rural areas of the central, southern and south-eastern states of the USA. Its beginnings are obscure - probably in Africa, but some even claim a connection with European medieval music - but its earliest published version was possibly 'Frankie and Johnny' (c. 1861), a song of cowboy origin.
Blues form is almost always of 12-bar length divided into three phrases of 4 bars each, the second phrase usually a repetition of the first, in both words and melody line, but based on the sub-dominant chord. At first a vocal music, it has since the early 1920s also been used for purely instrumental performances. Blues also exist in 8-bar and 16-bar forms.
For most of its life the blues has been closely allied with jazz, especially during the classic period, 1923 - 1931. Though jazz musicians continue to use its musical form, it has also been the basis of much country and western, rock and roll and pop music. Perhaps the best known composition is the 'St Louis Blues' by W. C. Handy, 1914, while the best-known singer is Bessie Smith.