I don’t want to go into a whole spiel about keeping fantasy worlds realistic because I’m no expert myself.
I used to wonder why fantasy worlds need to be realistic in the first place. After all, it is fantasy. Why can’t writers do whatever they want? Well, perhaps realistic is not the right word – it’s more about allowing readers to suspend belief and not keep questioning why things don’t make sense to them. So it’s really about keeping the fantasy world inherently logical – at least within its own confines.
Apart from paying attention to detail and reading over everything carefully to ensure the story makes sense from a logical perspective, writers often also have to research things in the real world that are common with their fantasy world.
For instance, if your fantasy world has horses, you should ensure that they resemble horses in the real world. Even though it’s fantasy, readers will scoff at horses that can run a hundred miles an hour for days without break or food (of course, you can always explain that it is a ‘magical horse’, but that may test the credulity and patience of some readers who have trouble suspending belief). Similarly, if your world has electric lights, the people should at least know about electricity. It’s a matter of keeping the world in line with the reader’s sense of reality and logic whenever possible.
Anyway, while doing some research on my own fantasy world, I came across a few articles that contain useful tips on how to keep the fantasy world realistic.
Most fantasy novels involve horses in one way or another, so it’s important to treat them right.
Here is an interesting website: Medieval Demographics Made Easy – Numbers for Fantasy Worlds. If your fantasy world resembles a medieval world in any way, you should at least take a look at this site. It provides factual information things such as population density, town populations, population spread, merchants and services, agriculture, castles etc. You don’t have to take these statistics into account but they are a good point of reference.
Battles are another common thing in fantasy novels. Here is an article on keeping the armies realistic, especially if they involve exclusively humans - The Numberless Hordes: Keeping Your Fantasy Armies a Little Less Fantastic by John Savage.
Here’s something that might come in handy. If you want to make your fantasy world really realistic, you might want to consider the history of plumbing at theplumber.com. It’s something that’s avoided in most novels but it doesn’t hurt knowing about it just in case.
There’s not much use of magic in my fantasy world but I thought I’d throw this in as this is about creating a fantasy world after all.
Three good articles: What is Magic Realism, Really? by Bruce Holland Rogers; What’s the Magic Word: Defining the Sources, Effects and Costs of Magic by Lital Talmor and Creating Believable Magic by Tina Morgan.
PS: Lastly, I just wanted to mention a couple of other resources – World Builder Resources, which has a ridiculous amount of links on building your world – definitely worth a visit; and Limyaael’s Fantasy Rants – a fabulous journal where Limyaael rants about things that annoy him in fantasy novels. You may not agree with everything he says, but his posts provide an incredible wealth of information about how to make your fantasy novel better and how to avoid making it worse.