The document discusses the origins and history of blues music. It began as a type of music developed by African Americans in the late 19th century. Blues music directly or indirectly influenced many popular music genres of the 20th century like jazz, rock, and R&B. The typical blues form has a 12-bar structure and three recognizable stylistic features: the blue note, call-and-response, and a three-line lyric structure. Early blues was recorded in the 1920s-1940s in both urban and rural settings, with different regional styles developing like Delta blues and Piedmont blues. Blues declined in popularity in the 1950s but saw a revival in interest and support in the 1960s to present day.