World building is creating the world your story happens in: its places, its people, and its rules. Start with the genre and a short premise, reveal the world bit by bit instead of all at once, keep notes so that you stay consistent, and draw a map.
When you write fiction, you need to work on your world building. It is about the place where your characters live and go on their quests, the place where everything happens. It also covers what your characters wear, eat, and enjoy, and the rules that govern their world.
Where to start
Start with the basics: decide on the genre. Once that is set, you can work on the premise, keeping the overall theme of your story in mind.
A premise is one short paragraph that describes your world, so that you get a feel for it. Remember, your world does not have to be huge to be interesting. It can be as small as a lush rice field where villains come to think about their past deeds, or an imaginary town where everything seems a little unreal.
Here is an example:
Kabutan is a small port village on the far western edge of Java. It is always covered in thick fog, which gave the village its name. An impassable stretch of dense forest surrounds it like a dragon, both protecting it and cutting it off from the outside world. Despite the gloomy setting, the villagers are always lively and full of energy. Children play all day while they wait for the adults to come home from hunting pirates for the bounties on their heads.
Avoid the info dump
You may be tempted to reveal everything at once, or to write a whole chapter that explains your world. Do not do it. Good world building is like water dripping steadily into a bucket. Give your readers enough to understand what is going on, and no more. As the story unfolds, reveal the details bit by bit.
Look for inspiration
Still not sure how to approach it? Take an idea or two from your favorite books. How did the authors build their worlds? Take note of the moments that made you marvel at how good they were. Science fiction and fantasy are full of examples; for a start, see 15 tips on how to write a science fiction story.
Be consistent
It is easy to contradict yourself as you write. As the story goes on, you may forget a thing or two. Small mistakes add up, and your readers will notice them even when you do not.
Keep notes on where everything is, which laws govern how your characters interact with the world, and what role each part of the world plays in the story.
Draw a map
Try drawing a rough map of your new world. It helps a lot when you want to picture it. You can draw it on paper or on your computer.
As your characters travel from place to place, a map in front of you also keeps things consistent. For example, if the beach is on the western side of the village and your hero is looking east, he cannot be watching a strange ship sail toward the shore.
World building is a basic part of storytelling, and like any skill it gets better with practice. Why not start by describing your own surroundings? Describe them in detail, then add something strange to them, just to get your creative juices flowing.