# Runestone A Runestone is a set of encoded directives stored within the OP\_RETURN field of a Bitcoin transaction. It serves as a blueprint for specifying the desired actions to be performed with Runes during that transaction. For instance, a Runestone can contain instructions such as "Mint this particular Rune," "Etch a brand-new Rune," or "Transfer these specific Runes." Without a Runestone, the default behavior is that all Runes present in the input UTXOs will be automatically transferred to the first non-OP\_RETURN output of the transaction. To deviate from this default and exercise more control, users can incorporate a Runestone and include an [Edict](https://x.com/rodarmor/status/1782551238116356567), which provides explicit instructions on which Runes should be routed to which outputs. Bitcoin currently imposes a limit of 80 bytes for data stored in the OP\_RETURN field. While typical Runestones comfortably fit within this constraint, more complex transactions involving the arbitrary distribution of multiple Runes across numerous outputs (such as [airdrops](https://www.investopedia.com/terms/a/airdrop-cryptocurrency.asp)) may necessitate a larger Runestone. Should Runes attain widespread popularity, the discussion around increasing Bitcoin's 80-byte OP\_RETURN size limit could gain traction, as it would allow for more intricate Runestone instructions to be accommodated. It's worth noting that most users are unlikely to interact directly with Runestones. Front-end providers are expected to abstract and streamline this process, offering a more user-friendly experience. --- # 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://book.runesterminal.io/4.-how-do-bitcoin-runes-work/runestone.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.