A riff is a repeated chord progression or melodic figure, often played by the bass instruments, that forms the basis or an important part of a rock music or jazz composition; an ostinato figure.
Examples of music that depend on riffs for their effect:
... United Kingdom as early as 1912.
Writers and artists in the United States such as F. Scott Fitzgerald, John Held, Jr.[?], and Anita Loos[?] popularized the flapper look ...