In January 2023 Casey Rodarmor launches the Ordinals protocol. Ordinal Theory numbers every one of Bitcoin's roughly 2.1 quadrillion satoshis, and inscriptions attach arbitrary data (text, images, code) to an individual sat. The data sits on-chain, timestamped by its block and copied by every full node, which makes it one of the most durable ways ever devised to store a digital record.
Contested history
Consensus: Inscriptions are valid under Bitcoin's consensus rules and have paid substantial fees to miners. Whether nodes should relay them is one of the most heated arguments in Bitcoin's history.
A legitimate use of block spaceMatter of opinion
Supporters argue that every inscription pays the market fee, that Bitcoin should be neutral about what its transactions carry, and that permanence is valuable.
Spam that should be filteredMatter of opinion
Critics argue that inscriptions raise the cost of running a node and crowd out payments. Some run Bitcoin Knots, which filters them by default.
Filters can stop inscriptionsDebated
Relay filters only apply to nodes that run them. Miners can still include inscriptions sent to them directly, and they do.
The 2025 OP_RETURN changeDebated
Bitcoin Core 30 relaxed its default limit on OP_RETURN data in October 2025, which reignited the dispute over data on Bitcoin.