In popular culture, formula fiction is literature in which the storylines and plots have been reused to the extent that the narratives are predictable.
It is similar to genre fiction, which identifies a number of specific settings that are frequently reused.
The label of formula fiction is used in literary criticism as a mild pejorative to imply lack of originality.
For any given genre, certain assumed background information covers the nature and purpose of predictable elements of the story, such as the appearance of dragons and wizards in high fantasy, warp drives and rayguns in science fiction, or shootouts at high noon in Westerns.
Note however that stereotypical elements can also easily be treated subversively, to contradict some of the expectations inherent in the genre's formula.