Ordinals & Inscriptions

💡 The Plain-English Definition

Ordinals is a protocol that assigns a unique serial number to every satoshi (the smallest unit of bitcoin, one hundred-millionth of a coin) ever mined. Inscriptions attach arbitrary data — images, text, code, video — to specific satoshis, creating Bitcoin-native digital artifacts permanently stored on the blockchain.

🤔 But Why Though?

Casey Rodarmor launched the Ordinals protocol in January 2023 with a simple but far-reaching idea: because satoshis are mined in a specific order and passed through transactions in a predictable way, you can track individual satoshis across the blockchain. The tracking uses a First In, First Out rule — the first satoshi to enter a transaction is assigned to the first satoshi to leave it — which preserves each satoshi’s identity through transactions. That gives every satoshi a unique ordinal number, from 0 (the first satoshi ever mined) up to roughly 2.1 quadrillion (the last that will ever be mined).

Inscriptions build on this. By attaching arbitrary data to specific satoshis using Bitcoin’s witness data — the part of a transaction that holds signatures, given a block-weight discount by the 2017 SegWit upgrade — those satoshis become carriers of content, permanently stored on the blockchain.

Technically it uses a two-step commit/reveal. One transaction first commits to a Taproot script (from the 2021 upgrade) containing the inscription data, and a second transaction then spends that output, revealing the data in the witness field. The data sits inside a standard tapscript envelope, wrapped in OP_FALSE OP_IF instructions that are never executed — so the data is present on-chain without affecting whether the transaction is valid.

The controversy is genuine and worth presenting honestly. Critics argue that Ordinals eat up block space meant for financial transactions, push fees up for ordinary users, and store content — JPEGs, memes — that has no place in a monetary network. Proponents argue that Ordinals show off Bitcoin’s programmability, generate fee revenue that strengthens long-term miner security, and draw in developer activity — and that block space is a market, so anyone willing to pay the fee is entitled to use it. Bitcoin Core v30.0’s removal of the OP_RETURN 80-byte limit in October 2025 partly reflects the pragmatic view that this data will end up on-chain regardless of node policy. On the other side, Bitcoin Knots — the alternative implementation maintained by Luke Dashjr — offers filtering for operators who want to exclude inscription transactions.

🌍 The Real-World Analogy

Think of the Bitcoin blockchain like a town’s official record book — historically used only for property deeds and legal agreements. Ordinals and inscriptions are like someone discovering the book’s paper is archival quality and deciding to press flowers into the margins, attach photographs to the pages, and store art between the legal entries. Traditionalists argue the paper is too precious for flowers — it’s for legal documents only. Others argue that if the paper is valuable enough for someone to pay the premium to use it, pressing flowers into it is a legitimate use of a public resource.