I think the success of the recent Batman Trilogy can be pined to one thing: a good back-story.
This may seem sundry, but it's true, and explains why in every single Superman movie we are forced through a sequence of footage detailing the same origin story. But it's necessary for this to happen, and this is why: We need to be involved with the character's origins, otherwise we can't track who they are and how they change in the narrative.
That's right, back-stories illustrate and establish something called narrative pacing. In the first Batman film, the film begins in medias res in the Chinese prison camp, and then puts the viewer through a sequence where Bruce pull's his name (literally) from the mud and simultaneously becomes the Batman. I think the reason why this back-story was so successful was probably in part due to its novelty, because in the previous
back-story the Batman is motivated by revenge and then executes the idealized justice we all crave. Nolan's Batman is thoughtful and intelligent, and entices the viewer to rebel against Bruce's Crusade and his dubious ethics.
How to execute this in a story, that is another question.
Narrative is a little different in a book, because, unlike film, there are no camera settings or light arrays that can be used to alter the mood and emotion in writing. However, when writing a good back-story you can get creative in how you overlay it into your writing. There are two approaches that I have seen work the best.
The "weaving" technique I prefer for its more subdued approach. This is where a back-story is inserted into the narrative through conversations that the main character has, or rather thinks in his consciousness. It would look like this:
Randal woke up, brushing a rough comb through his black wavy hair, waiting for the alarm clock to chime. The crack in its face was thin, barely a sliver, a reminder of his father's shaking. The tremors would come at any time, even at night. It was only a matter of time before the clock would strike the ground. He remembered reading 4:34am when they finally took his father.
Here, it is the clock that acts as a narrative vehicle to tell the story of Randal and how his father died.
The second technique has no name for it, mostly because I am not clever enough to make one. Laying back-story can simply be explained outright, in the form of narrative exposition, like seeing the Star Wars reel move up the screen with all the text ready to tell us what has happened. This again might not be as interesting, but It can be iconic. Neil Gaiman takes this approach in Stardust. The narrative begins with exposition that lays out what the core of the book will consist of, primarily in the town of Wall and the Faerie market, thereby explaining Tristan's uncanny origins. This also establishes the dichotomy between fantasy and reality which comes into play throughout the book. If you've never read it, I highly recommend checking it out.
Anyways, that's in a nutshell what makes a good back-story. Hope you found it helpful!