Ordinals

Launched on Bitcoin mainnet by developer Casey Rodarmor on January 20, 2023, Ordinal NFTs are simply the latest way to create NFTs on Bitcoin. Ordinals are means of creating Bitcoin NFTs by attaching data such as images, videos, and more to an individual satoshi on the base Bitcoin blockchain. Unlike their predecessors, ordinal NFTs don’t exist on a separate layer from Bitcoin. Rather, they use an arbitrary but logical ordering system called ordinal theory to give each individual Bitcoin satoshi a unique number. In this regard, ordinal NFTs are completely Bitcoin-native. They work without changes to the Bitcoin protocol, don’t require any extra layers, and are backward compatible with the network.

Ordinals are a numbering scheme for satoshis that allows tracking and transferring individual sats. These numbers are called ordinal numbers. Satoshis are numbered in the order in which they’re mined, and transferred from transaction inputs to transaction outputs first-in-first-out. Both the numbering scheme and the transfer scheme rely on order, the numbering scheme on the order in which satoshis are mined, and the transfer scheme on the order of transaction inputs and outputs. Thus the name, ordinals.

Technical details are available in the BIP.

Ordinal theory does not require a separate token, another blockchain, or any changes to Bitcoin. It works right now.

Ordinal numbers have a few different representations:

• Integer notation: 2099994106992659 The ordinal number, assigned according to the order in which the satoshi was mined.
• Decimal notation: 3891094.16797 The first number is the block height in which the satoshi was mined, the second the offset of the satoshi within the block.
• Degree notation: 3°111094′214″16797‴. We’ll get to that in a moment.
• Percentile notation: 99.99971949060254% . The satoshi’s position in Bitcoin’s supply, expressed as a percentage.
• Name: satoshi. An encoding of the ordinal number using the characters a through z.

Arbitrary assets, such as NFTs, security tokens, accounts, or stablecoins can be attached to satoshis using ordinal numbers as stable identifiers.

Ordinals is an open-source project, developed on GitHub. The project consists of a BIP describing the ordinal scheme, an index that communicates with a Bitcoin Core node to track the location of all satoshis, a wallet that allows making ordinal-aware transactions, a block explorer for interactive exploration of the blockchain, functionality for inscribing satoshis with digital artifacts, and this manual.