All Transfer API classes are marked as @ApiStatus.Experimental. This is temporary, and it means that there may be occasional breaking changes if a design flaw is encountered in the API, but we will try not to break the API to avoid disrupting the large amount of mods that are using it already. In practice, this means that you can mostly ignore this warning, and disable it in your IDE if it's too annoying.

The Fabric Fluid Transfer API is how fluid-containing blocks such as machines, pipes, and tanks communicate with each other. It's what allows all mods to be compatible with each other as far as fluid transfer is concerned. (If you are coming from Forge, it serves a purpose similar to IFluidHandler).

1. Creating a tank block entity walks you through how you can create a simple tank block entity, and what FluidVariant is.
2. Understanding Storage<FluidVariant> teaches what Storage<FluidVariant> is and how to use it.
3. How to implement Storage<FluidVariant> provides an overview of the storage implementations provided by Fabric that you can use in your mods, with plenty of example code.

The Fabric Item Transfer API is used by item-containing blocks such as chests, machines, or storage drawers to communicate with other. (If you are coming from Forge, it serves a purpose similar to IItemHandler).

1. Item transfer with Storage<ItemVariant> explains how the item API is almost the same as the fluid API, how wrappers around Inventory/PlayerInventory can be retrieved, and how item storages can be implemented in practice.

Note: the existing item transfer API in Minecraft should be avoided in fabric mods due to its severe limitations. If you don't know what this means, you can ignore this warning.

1. [Not finished] How to use and implement the fluid-containing item API.

1. [Not yet written] 1. how to create an energy storage block entity