This is a story book. A sequel (also known as follow-up) is a narrative, documental, or other work of literature, film, theatre, television, music, or game that continues the story of, or expands upon, some earlier work. In the common context of a narrative work of fiction, a sequel portrays events set in the same fictional universe as an earlier work, usually chronologically following the events of that work. In many cases, the sequel continues elements of the original story, often with the same characters and settings. A sequel can lead to a series, in which key elements appear in a number of stories. Although the difference between more than one sequel and a series is somewhat arbitrary, it is clear that some media franchises have enough sequels to become a series, whether originally planned as such or not. Sequels are attractive to creators and to publishers because there is less risk involved in returning to a story with known popularity rather than developing new and untested characters and settings. Audiences are sometimes eager for more stories about popular characters or settings, making the production of sequels financially appealing.