This post is completely double-edged. Not only is history important in terms of the setting and plot, but characters as well.
So, triple-edged sword?
My friend, Hannah, wrote a post on her blog about a month ago, encouraging her readers to explore the history of their worlds. To put it in her words: "Every setting has a backstory. Every neighborhood sits with a silent--or not so silent--story, waiting to be heard."
And she's right. Like always.
Cities, countries, empires, etc. didn't just pop into existence from nothing, and neither did whatever setting you're working with. There were settlements by outside people, clashes with natives, wars-so many wars-and finally something that looks like peace (*snorts*) in the present-day United States. I just finished reading The Pledge, by Kimberly Derting, and we're given a mini-history lesson about why there's only queens, why there's no presidents or ministers or any male leader whatsoever within the countries that now inhabit the world.
The history of a place is important. While you don't have to spill every detail about it within the span of your novel, it's an important aspect of the author to understand so that they can create a world that's consistent with events that happened in the past.
History also has a huge impact on the plot. I gave an example above about The Pledge: at one time in the history of this world, there were royal families who lead their countries. Eventually they were brought down in favor of other leaders, which didn't work out too well. So, the people took them down, too, and reestablished the rule of queens which, for the most part, has worked out.
This history, and the fear of repeating it, is so strong that the people are adamant that, while the current queen must be brought down, there has to be another queen to take her place.
No parliaments or Congresses. No presidents, senators, or representatives. A queen.
History often acts as a lesson for the present and the future. It scares people into making laws and creating societal order that might crumble sooner or later, but it's better than what used to be. And when it does fall, then it, too, becomes a lesson. Understanding the history of your world can have a direct impact on the events that befall your characters, depending on how much of it the characters know and understand, and it can affect the way they think and the way they act, and thus somewhat dictates their actions.
This is actually a really great lead-in to:
The history of a certain character will legitimately shape their attitudes and the way they see their world when they're older. For example: in Cinder, the main character has been raised under the awfulness of her step-mother/guardian and the prejudices of everybody else who knows she's a cyborg. So she's kind of bitter, and hardened. And because people don't tend to pay attention to her, the moment somebody does (like the Prince) she finds herself willing to think about them in different ways.
Characters who are brought up around money with parents who give them everything they've ever wanted will tend to be a bit more on the bratty and privileged side, while those raised around money with parents to expected perfection out of them in return might be more stressed, even quiet, and probably a bit more rebellious.
Was your character ever abandoned by somebody, or betrayed, or they've spent most of their lives alone? They probably don't trust easy.
This might border more on psychology, as well, but the experiences that face a character during their lifetime shape them; their histories make them who they are and determine their thought processes and instincts. So knowing your characters' histories, as well, is an immensely important aspect of a novel, even though the majority of it might never be read by your audience.
Thoughts or questions? Let me know!