Frame Narrative
In literature, a frame narrative is a story that allows for the telling of other stories. Usually, the frame narrative is of minor importance or development, and the interpolated narratives are the main business of the fiction.In Canterbury Tales, for example, there is a story of pilgrims traveling to Canterbury, but this provides a setting for the pilgrims to tell a series of tales. In the Decameron, characters fleeing the plague tell a series of one hundred stories. In Frankenstein, a ship is stranded on the ice, and this allows Victor Frankenstein to come aboard and narrate most of the action of the novel as a flashback.
To be a frame narrative, the story must act primarily as an occasion for the telling of other stories. If the framing narrative has primary or equal interest, then it is not usually a frame narrative. For example, Odysseus narrates most of the Odyssey to Nausicaa, but, even though this recollection forms a great part of the poem, the events after and before the interpolated recollection are of greater interest than the memory.