Worlds live inside the instance they were created in, under saves. There is no shared world folder, which is what makes removing an instance safe for everything else you own.
Finding them
Open the Instances page, press Manage on the instance and then Open game folder, then open saves. Each world is a folder containing its region files, its level data and its player data. Copying the folder copies the world.
Backing one up properly
- Quit Minecraft first. A world folder copied while the game is running is a world copied mid-write, and it will occasionally fail to load.
- Copy the whole world folder — not only the
regiondirectory. The level data is what makes it a world. - Zip it if you are keeping more than a couple. World folders are mostly compressible region data.
Opening a world in a newer Minecraft version upgrades it, and that upgrade cannot be undone. Keep the backup until you are sure you want the upgrade.
Moving a world to another instance
Copy the world's folder from one instance's saves into another's. It will load if the target version is the same or newer. Mods the world relies on — custom blocks, entities, biomes — will be missing on the other instance, and Minecraft will report that when it opens it.
Server worlds
A multiplayer world's data lives on the server, not in your launcher. What you have locally is a cached copy of the chunks you have seen; deleting it costs you nothing but a re-download the next time you join.
Screenshots
Screenshots are saved to the instance's own screenshots folder, which is why two instances do not interleave their images. The same folder is reachable from the instance's Manage panel.