Custom world generation

Custom world generation allows data packs to change how the world generates. This is particularly useful in conjunction with custom worlds.

Biome categories
Biome categories are used by several game mechanics:


 * Any biomes in the category  will be considered part of the ocean temperature category; other temperature categories are controlled by the biome's temperature value. This means that biomes in the   category should typically be placed near each other.
 * Biomes in the categories  and   will play the underwater music instead of their normal music when the player is underwater.
 * Zombie sieges and patrols will not spawn in biomes in the category.
 * Rabbits spawning in biomes in the category  will always have the desert skin, unless they are in a biome with   set to.
 * Mobs in the  category spawn much less often in biomes in the category.
 * Ocean monuments will not spawn in any biome which isn't in the category  or.

Carvers
Carvers are used to add carved out regions of biomes, either replaced with air or liquid.

Surface builders
Surface builders control how the surface of the terrain is shaped and what blocks it is generated with.

Jigsaw pools
Jigsaw pools or template pools are used to generate structures using jigsaw blocks