# 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) --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://wiki.havenprotocol.org/overview/fluffy-blocks.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.