Blues music is based on a unique scale that blends minor and major chords. The structure of the blues allows for improvisation, or for the performer to make up parts of the music within certain rules. Instrumental music is important in the blues, but the lyrics play a key role in many songs. Rather than simply tell a story, blues singers express their feelings. This makes the songs both powerful and sad.

The blues began in the American South, where, in the time of slavery, blacks sang as they labored in the fields. These work songs became the basis for blues music. Southerner W. C. Handy, called the “father of the blues,” wrote down and played the music he heard in his youth. Through his songs, such as "Memphis Blues" (1911) and "St. Louis Blues" (1914), Handy helped make blues music popular. The first blues recordings were made in the 1920s by black women such as Mamie Smith, Ma Rainey, Ida Cox, and Bessie Smith.

In the first half of the 20th century many blacks moved from the rural South to Northern cities, and they brought the blues with them. Musicians in Chicago played the biggest role in developing urban, or city, blues. Some famous blues performers are Riley “B.B.” King, John Lee Hooker, and Buddy Guy. Blues music has also influenced other musical styles such as jazz, rock, and soul.