Behavior pack

The behavior pack system is a data-driven framework used to define behaviors, characteristics, and logic of various things in a Minecraft world.

Behavior pack serves as the foundational layer for many aspects of the game, dictating entity behaviors,[1] loot tables,[2] spawn rules,[3] item behaviors,[4] item recipes,[5] biome characteristics,[6] world generation, and much more. These definitions are written in JSON files, which are organized in multiple folders by their features. This system allows users to override and modify certain features in the base game, or add unique features with their own behavior pack. Behavior packs are often used in conjunction with resource packs as part of an add-on, which enable them to use custom resources, such as models, animations, textures, sounds, and more.

Behavior pack provides a component-based system that makes up most entities (and other game objects) in the game by describing their unique properties and behaviors — like health, collision box, movement, mob behaviors, and physics — through multiple components.[7] These components are hard coded in the game, but are commonly shared among entities, and can be used extensively to create or modify existing entities in a behavior pack. Molang can be used to quickly determine dynamic values from other objects or calculations. A similar feature in Java Edition would be entity attributes, but they only store numeric properties of entities compared to components, which may store other multi value properties.