Light music interprets music in a popular way, and its source can be original, or it can be adapted from classical music, pop music or folk songs. Light music is generally played by small bands, with simple structure, lively rhythm and beautiful melody. Light music can create a warm and romantic mood with a casual nature, hence the name "Mood Music". Light music originated in Britain after World War I, reached its peak in the middle and late 2th century, and was gradually replaced by new era music at the end of the 2th century, but it still has some influence today. Rock and Roll is a type of music, which originated in the United States in the late 194s, and became popular in the early 195s, and quickly swept the world. Rock music is loved by young people all over the world because of its flexible and bold expression and passionate music rhythm. Rock music became a craze in the 196s and 197s.