This is because the beginner writer doesn't trust the reader enough, assuming he won't understand without all the back-story as soon as possible; and at the same the beginner writer trusts the reader too much - trusts that he will hang around while all the tedious back-story is thrown at him.
Back-story is essential, but so, in my life, is coffee. This does not mean I should drink my daily
Perhaps the most common way to overdose on back-story, and therefore the one to beware of most, is this: Chapter One, full of excitement and the clever trailing of intriguing hooks, with the introduction of a character we really, really care about and are desperate to follow; Chapter Two, a history lesson in which our main character’s life story is laid out in meticulous detail. Result: either the reader skips it, or she becomes so disengaged that she couldn’t give a damn about Chapter Three.
I have noticed something in my own writing process, and other writers say they do this too. I tend to fill the first 5,000 words with lots of explanatory detail, because I am trying to get the situations and motivations clear in my own head. Then, on revising, I cut a huge amount of it out, because I realise that as long as it all hangs together and makes sense, the reader does not need nearly as much explanation as I’d thought. In effect, the explanation was for me, not the reader.
So, back-story needs to be drip-fed, gently, so that the reader never skips over it and hardly notices that it’s happening. I have come to realise that we need far less back-story than we often think. But we need enough. Enough for the reader, not for the writer.
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