Boogie-woogie, also known as boogie, is a genre of blues music that became popular during the late 1920s, but had already developed in African-American communities since the 1870s. It was eventually extended from piano to piano duo and trio, guitar, big band, country and western, and gospel. While standard blues traditionally expresses a variety of emotions, boogie-woogie is mainly dance music. The genre had a significant influence on rhythm and blues and rock and roll.