Blues music sprang from the humblest of beginnings. It derived from field hollers and spirituals of Southern slaves to become the essential bedrock of jazz, rhythm-and-blues, and rock 'n roll. What began as the outward expression of a life of misery and subjugation became, in the end, a celebration of life's joys and sorrows. Musically, the blues has several well-defined forms; those forms, once learned, allow musicians to freely improvise and pour their heart and soul into the music. Herewith follow some of blues' greatest artists...