Outdated page and not necessary.

Minecraft has registries for many kinds of objects, such as blocks, items or entities. These are the registries in vanilla:

The page is outdated. For version 1.19.3 and above, please replace Registry with Registries.
Some of the reigstries may not exist in latest versions, as they are data-driven. For example, you cannot find biome registries in Registry.BIOME and Registries.BIOME. However, their registry keys exist in RegistryKeys.BIOME. More information see registry_keys.

These registries are useful for many types of mods.

• Registry.REGISTRIES
  • Contains all the registries themselves.
• Registry.BLOCK
  • Contains all blocks.
• Registry.ITEM
  • Contains all items (including block items).
• Registry.BLOCK_ENTITY_TYPE
  • Contains the BlockEntityType of each block entity. Block entity types are used to deserialize block entities and store compatible blocks.
• Registry.STATUS_EFFECT
  • Contains all status effects, like invisibility or night vision.
• Registry.PARTICLE_TYPE
  • Contains all particle types.
• Registry.FLUID
  • Contains all fluids.
• Registry.ENCHANTMENT
  • Contains all enchantments.
• Registry.POTION
  • Contains all different potion types, such as “long potion of night vision”, “water” or “potion of luck”.
• Registry.DIMENSION_TYPE
  • Contains all dimension types.
• Registry.SCREEN_HANDLER
  • Contains all screen handlers. Screen handlers are used to synchronize GUI state between the server and the client.
• Registry.RECIPE_TYPE
  • Contains all recipe types
• Registry.RECIPE_SERIALIZER
  • Contains all recipe serializers. Recipe serializers are used to load recipes, and there can be many serializers for a single type (such as both shaped and shapeless crafting recipes).
• Registry.PAINTING_MOTIVE
  • Contains all painting motives, or the different types of paintings.
• Registry.SOUND_EVENT
  • Contains all different sound events like entity.item.pickup.
• Registry.STAT
  • Contains all different stat types. Stats use a generic type, <T>, to get different data for different T values.
    • Stats that don't depend on outside objects (eg. walk_one_cm) use the custom stat type, which uses registered Identifiers as the T type.
    • Stats that aren't custom stats might depend on a specific block or item type, like Stats.MINED.
• Registry.CUSTOM_STAT
  • Contains all “custom stats”, which are identifiers for stats that don't depend on outside objects.

Most of these registries, apart from ENTITY_TYPE itself, are related to entity AI.

• Registry.ENTITY_TYPE
  • Contains the EntityType of each entity. Like block entity types, entity types are used for syncing and deserialization.
• Registry.SCHEDULE
  • Contains schedules for entities (usually villagers). Schedules control their activities based on the time of day.
• Registry.ACTIVITY
  • Controls activities for entities (usually villagers). Activities, such as play or work, control the behavior of entities.
• Registry.SENSOR_TYPE
  • Contains the type of each entity sensor. Sensors allow entities to “sense” different things and store them in their memory.
  • Like schedules and activities, this is mostly used by villagers.
• Registry.MEMORY_MODULE_TYPE
  • Contains all types of memory modules. Memory module types describe different things entities can remember.
• Registry.VILLAGER_TYPE
  • Contains all villager biome types.
• Registry.VILLAGER_PROFESSION
  • Contains all villager professions.
• Registry.POINT_OF_INTEREST_TYPE
  • Contains all types of points of interest. Points of interest allow entities to search for different blocks in the world, such as villager job sites. They are also used to locate nether portals.

World generation in Minecraft is complex, and there are a lot of different registries for world gen.

• Registry.BIOME
  • Contains all biomes.
• Registry.FEATURE
  • Contains all world generation features, including structures.
• Registry.STRUCTURE_FEATURE
  • Contains all structure features.
• Registry.CARVER
  • Contains all carvers. Carvers are used to create caves and ravines.
• Registry.DECORATOR
  • Contains all decorators. Decorators are used to place features.
• Registry.BIOME_SOURCE_TYPE
  • Contains all biome source types. They determine which biome is placed where during world generation.
• Registry.TREE_DECORATOR_TYPE
  • Contains all tree decorator types. Tree decorators can add additional blocks, such as beehives or vines, to trees.
• Registry.FOLIAGE_PLACER_TYPE
  • Contains all foliage placer types. Foliage placers are used to generate the leaves of trees.
• Registry.BLOCK_STATE_PROVIDER_TYPE
  • Contains all block state provider types. They are used to select a possibly random block state based on a position.
• Registry.BLOCK_PLACER_TYPE
  • Contains all block placer types. Block placers are used to place blocks in features like RandomPatchFeature.
• Registry.CHUNK_GENERATOR_TYPE
  • Contains all chunk generator types. Chunk generators define the basic shape of the terrain, such as surface for overworld-like, caves for nether-like and floating_islands for end-like terrain.
• Registry.CHUNK_STATUS
  • Contains all chunk status types. They describe the current progress of world generation in a chunk.
• Registry.STRUCTURE_PIECE
  • Contains all structure piece types. Structure pieces are smaller parts of a structure, such as a single room.
• Registry.RULE_TEST
  • Contains all rule test types. They are used to match blocks in structure generation.
• Registry.STRUCTURE_PROCESSOR
  • Contains all structure processor types. Structure processors modify structures after they have been generated.
• Registry.STRUCTURE_POOL_ELEMENT
  • Contains all structure pool elements. Structure pool elements are even smaller parts of structures, and they are contained within pool structure pieces. They are used for generating structures that are based on datapacks (such as structures using jigsaws).
• Registry.SURFACE_BUILDER
  • Contains all surface builders. Surface builders are used to place the surface blocks of a biome, such as grass in many overworld biomes.