Blues

Blues was originated in the Deep South of the United States around the 1870s by African-
Americans from roots in African musical traditions, African-American work songs, and
spirituals. Blues incorporated spirituals, work songs, field hollers, shouts, chants, and
rhymed simple narrative ballads. The blues form, ubiquitous in jazz, rhythm and blues and
rock and roll, is characterized by the call-and-response pattern, the blues scale and
specific chord progressions, of which the twelve-bar blues is the most common. Blue notes
(or "worried notes"), usually thirds, fifths or sevenths flattened in pitch are also an
essential part of the sound. Blues shuffles or walking bass reinforce the trance-like
rhythm and form a repetitive effect known as the groove.