Flashback

A flashback, more formally known as analepsis, is "an interjected scene that takes the narrative back in time," most often used to recount events from before the story's primary sequence "to fill in crucial backstory." Narratology splits the device: "internal analepsis is a flashback to an earlier point in the narrative; external analepsis is a flashback to a time before the narrative started." The device is old. The Ramayana and Mahabharata tell their main stories inside later frame stories, the Arabian Nights tale "The Three Apples" is an early murder mystery built on flashbacks, and film made the technique famous, from the 1901 Histoire d'un crime to Citizen Kane, which unfolds a whole life through a reporter's interviews.

For the writer a flashback is borrowed authority: the past arrives as a lived scene rather than a summary, buying emotion at the price of pausing the present line. Keeping the true chronology straight across viewpoint chapters is the job of timelines across POVs and flashbacks, and stacked flashbacks are one engine of a nonlinear narrative.