Narrative Structure

Three Act Structure

Generally, the narrative structure of any work, be it a film, play or novel, contains a plot, theme and resolution. 

It can also be divided into three sections, which is referred to as 

The three-act structure: Setup, Conflict and resolution.  

The setup (act one) is where all of the main characters and their basic situation are introduced, and contains the primary level of characterization (exploring the character's backgrounds and personalities). 

A problem is also introduced, which is what drives the story forward.

The second act, the conflict, is the bulk of the story, and begins when the inciting incident (or catalyst) sets things into motion. This is the part of the story where the characters go through major changes in their lives as a result of what is happening; this can be referred to as the character arc, or character development.

The third act, or resolution, is when the problem in the story boils over, forcing the characters to confront it, allowing all elements of the story to come together and inevitably leading to the ending.

Linear and non-linear narrative structures

A non-linear narrative is one that does not proceed in a straight-line, step-by-step fashion, such as where an author creates a story's ending before the middle is finished.
Linear is the opposite, when narrative runs smoothly in a straight line, when it is not broken up.

Flashback movies are often confused with true non-linear narratives.
Although they appear to open (very briefly) with the ending, flashback movies almost immediately jump back to the very beginning of the story to proceed linearly from there and usually proceed past the supposed "ending" shown at the beginning of the movie.

A classic example of a non-linear narrative is the 1994 film Pulp Fiction. The film is ostensibly three short stories, which, upon closer inspection, are actually three sections of one story with the chronology broken up; no "flashbacks" are involved.