Blues are a kind of music that developed in America from the various musical expressions of African Americans. The blues are an extremely flexible type of music, and various musicians have created individual styles of performing them. The blues contributed greatly to the development of jazz. Such jazz musicians as Duke Ellington, Charlie Parker, and Jack Teagarden have often included variations of the blues in their music. In addition, some classical music and numerous rock, folk, and country music compositions also show the influence of the blues.

The basic blues design is a 12-bar form that is divided into three sections of four bars each. Most blues lyrics consist of several three-line stanzas. The second line of each stanza repeats the first, and the third line expresses a response to the first two. Many blues lyrics reflect loneliness or sorrow, but others declare a humorous or defiant reaction to lifes troubles.

Blues may have developed after the American Civil War (1861-1865) from short solo calls and wails called field hollers. Field hollers were used as a form of communication among black plantation workers in the South. In the late 1800s, country, or "down-home," blues developed in the Mississippi Delta region. These songs were sung by a male singer, usually with the accompaniment of a guitar. Blind Lemon Jefferson and Mississippi John Hurt were well-known singers of country blues.

The blues became more widely known in the early 1900s. A bandleader named W. C. Handy began to publish blues songs that won wide popularity. Handys compositions include "Memphis Blues" (1912) and "St. Louis Blues" (1914). In the 1920s, Bessie Smith emerged as one of the most talented and popular of the classic blues singers. Recordings by Bessie Smith, Mamie Smith, Ethel Waters, and others helped bring urban blues to a larger audience. In the 1930s, boogie-woogie, a blues-influenced style of piano music, became popular.