> For the complete documentation index, see [llms.txt](https://wiki.havenprotocol.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wiki.havenprotocol.org/overview/fluffy-blocks.md).

# Fluffy Blocks

#### The Basics

A @block is made up of a header and @transactions. Fluffy Blocks only contain a header, a list of transaction indices, and any transactions that the node recieving the block may be missing. This saves bandwidth because nodes might already know about most or all of the transactions in the block and they don't need to be sent them again.

#### See Also

* [BIP152 "Compact Block Relay"](https://github.com/bitcoin/bips/blob/master/bip-0152.mediawiki)
* [Xthin](https://github.com/BitcoinUnlimited/BitcoinUnlimited/blob/release/doc/bu-xthin-protocol.md)


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