Just like with planning characters, the amount of world building that needs to be done really depends on the story. And the writer. But mostly the story.
If you’re writing a contemporary, you probably don’t need to do a lot of world building. The world already exists. You might need to figure out some details. Maybe you’ll need to look up a map of a specific city, or you know the layout already because you’ve been there. Maybe you don’t even need the specific layout of a place, you just need to know what the suburbs are like.
If you’re writing a story that is not set in the real world, you’re going to have a lot more world building to do. Probably. My favorite thing about a story set in a fictional world, is the map. I love books that have maps in them. It’s the visual learner in me. Maps are helpful, even if you don’t give them to the reader, if your characters are going to be travelling. Or if international relations matter. Even if your characters aren’t going far, cities and towns are effected by their geography. The weather, the economy, the access to travel routes. The way people live is effected by where they live.
Outside of the physical location of your story, you may have some science to figure out or a magic system to create. If spaceships are common, that’s part of the world. If people have magical powers, that’s part of the world. You should have a basic understanding of how your world work, even if you don’t understand how these specific things work, y’know, since they don’t. We don’t have magic or time travel in the real world. But, if using magic can exhaust a person, you should know that. If magic can’t create things, it can only manipulate them, you should know that. You don’t have to know why or how, you just have to know that it is.
When in doubt, less is more. You don’t need to know how a spaceship would work in our world, but you need to know that spaceships work in your world. You should know that they run on fuel. They have mechanical and electrical parts. This may be important if you decide to break your characters’ spaceship at some point. But if you try to get specific and explain what part is broken and how to fix it, your readers will know. They’ll see right through your lies and you’ll risk breaking the elaborate, immersive world you created. Sometimes, they just need to know that the ship is broken, and someone made a temporary fix with some spare parts and some quick thinking that will last long enough to land, rather roughly, on the nearest planet where they will pay more than they would like for the unnamed part and then repair the ship properly. A small price to pay so they can save the universe.
You don’t have to know everything, and you certainly don’t have to explain everything to the readers, but you should know the base of how your world works. Everyone rides to work on their own personal hover boards and pays for things with chips embedded in their wrists. I don’t have to tell you why those things work or how. They just do. It’s my world. All you need to know is my main character paid for her hover board repair by swiping her wrist over a scanner at the repair shop and now she knows she’ll be living off of instant noodles for the next few weeks to make up for it.
It’s your world. You can do whatever you want. Just remember, if you tell the readers that something is, they have to accept it, but you have to make them believe it.
What’s your favorite thing about your story’s world?