Bitcoin Ordinals is a numbering scheme and inscription protocol that assigns a unique serial number to every individual satoshi on the Bitcoin network based on the order of its mining, enabling arbitrary content — text, images, code — to be embedded directly into Bitcoin transactions via the witness data introduced by SegWit and Taproot. Each inscription is permanently stored on-chain without requiring a separate token contract, making it a native non-fungible artefact within the Bitcoin base layer. The protocol was introduced by Casey Rodarmor in January 2023.
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- The Ordinals theory was formalised by Casey Rodarmor and published in January 2023, drawing on prior academic work on coloured coins and leveraging the expanded witness capacity unlocked by the 2021 Taproot upgrade. The key insight was that satoshis, as the atomic unit of Bitcoin, could be given permanent identity through their mining order without modifying Bitcoin’s consensus rules — inscriptions are valid transactions from the perspective of every existing node.
- Technically, an inscription is created in two transactions: a commit transaction that locks funds to a Taproot output, and a reveal transaction that spends it and embeds data in the witness script using a series of
OP_FALSE OP_IF ... OP_ENDIFopcodes. Content is MIME-typed and stored verbatim, so images, HTML, JavaScript, and even small applications can be inscribed. The ordinal number of the first input satoshi is conventionally treated as the inscription’s ID. - The ecosystem around Ordinals developed rapidly through 2023 with marketplaces such as Magic Eden and Gamma, indexing services including the
ordcommand-line tool, and wallets adding sat-control features to avoid accidentally spending inscribed satoshis. BRC-20, an experimental token standard layered on Ordinals using JSON inscriptions, further increased transaction volume and generated significant controversy over Bitcoin’s purpose. - By 2024–2025 Ordinals had generated over 60 million inscriptions and produced transaction fee spikes that temporarily exceeded block subsidy — a phenomenon Bitcoin advocates had long theorised but not witnessed. Debate continues within the Bitcoin community about whether on-chain data storage is an appropriate use of block space, whilst artists and developers continue to explore Bitcoin as a permanent, censorship-resistant inscription medium.