I've been thinking recently about world-building. Apparently I'm good at it. I have a feeling this might be to do with hours and hours spent daydreaming, but I'll take it as a compliment.
What does world-building actually mean? I'm not sure if there actually is a definition, but to me, it means creating a fictional world your reader can believe in. Doesn't matter if it's contemporary, historical, or the planet Zharg: it's got to be believable.
How do you do that? Well, you make the world work. This probably requires more work if you're writing out-and-out fantasy than if you're writing a contemporary, but don't think you can sit back and relax. You still need to convince the reader that the world of your books exists. Don't assume she's familiar with it just because it's set in a real place. Odds are, she doesn't know that place, so you've got to create it for her. What does it look like, and smell like, and sound like?
While I'm on the subject, let me talk about one of the things prompting my thoughts about world-building. Facts: getting them wrong. I can't count the times I've been yanked out of a book by a fact I know to be blatantly wrong; or even just one that feels inaccurate. It happens most with historicals. Right now I'm finding myself intensely irritated by a book set in 1830 England, in which the heroine seems to be wearing a lot of outfits gathered just below the bust, showing off her waist, hips and legs, and allowing her to sit in one scene with her knees drawn up to her chin. In 1830? No corset, no miles of petticoats? My Evolution of Fashion notes for 1830 that the skirts can be up to 11 feet in circumference, that the bodice as well as the corset is boned, that even the sleeves are stiffened and padded, and pads are worn under the dress to exaggerate the shape of the skirts. Not quite a flimsy, form-revealing gown.
What that little tirade is meant to demonstrate is that the inaccuracies in research pulled me out of the story. Yes, gentle reader, they even made me go and get my costume books. They made me lose faith in the author and her ability to sustain a believable world. After all, if she couldn't even get the style of dress right, what else might go wrong? I started noticing every description of the surrounding world, from the leaves on trees to the forms of address between characters. I started to doubt that this world did, had, or ever could exist.
And that got me thinking. Is it all about the detail? No: I've read plenty of books that were very light on the detail, purposefully, to keep me in suspense, and never once felt like I was being cheated. Is it about accuracy? Again, not necessarily. Some books take enormous liberties, by accident or design, but they still don't pull me out of the story. Is it about creating parameters? I believe the author needs them more than the reader does.
So what is it, then, this elusive 'world-building' that makes you believe in a fictional world? I'm still working on my own definition, but while I do that, let me leave you with a few words from a man who has created a flat world that flies through space on the back of a giant turtle, where animated rocks join the police force and witches who can't spell are able to make a whole country travel in time--but a world which, nevertheless, makes total sense to me.
I tended to distrust fantasy cities when I was a kid. They were too much like stage sets. They didn't seem to operate. A city of even half a million takes a hidden army of farmers, fishermen and carters just to see it through the day. We have lost sight of that, now that food grows on supermarket shelves and there are bright kids who don't know what 'ploughing' means. But a humdrum city day requires a thousand unseen things to happen like clockwork, because it is only a couple of hours away from chaos.
Over the series I've tried to capture the feeling of a city that would go on running even if the story stopped. Somewhere in the background all those people would go on baking bread, making pins, shoeing horses--and bringing in the food.
Sir Terry Pratchett, The Art of Discworld
Perhaps that's the key. A world that works, and one which isn't set up just for the purposes of your story. After all, your hero and heroine might think the story's all about them, but the shopkeeper on page 45 probably thinks the same thing about himself...