A back-story is a literary device[?] often employed in order to lend a story depth or verisimilitude. Characters or events related to a story may only be given cursory treatment so as not to distract from the central plot development.
Probably the most extensive back-story ever created was that created by J. R. R. Tolkien for his Middle-earth stories.
... for a family is $80,748. Males have a median income of $41,917 versus $46,313 for females. The per capita income for the town is $28,614. 7.9% of the population and ...