Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Radical Folk is a modern variation of folk music that keeps a traditional sound and tackles more modern issues. The term folk music originated in the 19th century as a term for musical folklore. It has been defined in several ways; as music transmitted by word of mouth, music of the lower classes, music with no known composer. It has been contrasted with commercial and classical styles. Since the middle of the 20th century the term has also been used to describe a kind of popular music that is based on traditional music. Fusion genres include folk rock, electric folk, folk metal and progressive folk music.