Item format/Before 1.20.5

Items are used both in the player's inventory and ender chest, in container block entities, in some item entities, and in structure files.

Items are stored in the NBT format. Sometimes a [Byte] Slot tag is used to specify the slot the item is in, such as with chests; other times there is no [Byte] Slot tag, such as with dropped items.

All items can have custom display names and lore, as well as a custom model data. Various tooltips can also be hidden.