> For the complete documentation index, see [llms.txt](https://book.runesterminal.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.runesterminal.io/2.-origins/ordinal-theory-ordinals.md).

# Ordinal Theory (Ordinals)

[Ordinal Theory](https://docs.ordinals.com/) is the numbering scheme that assigns unique identifiers to individual satoshis - the smallest units of Bitcoin. These ordinal numbers track satoshis in the order they're mined and transferred between transaction inputs and outputs on a first-in-first-out basis. 

Both the numbering and transfer mechanisms rely inherently on order - the numbering on the mining order, and transfers on the input/output order. Hence the name, ordinals.

Ordinals require no separate tokens, auxiliary blockchains, or Bitcoin protocol changes. It works natively with Bitcoin's existing architecture.

Ordinal numbers have multiple representations:

* Integer Notation: 2143094100742059 (The ordinal assigned by mining order)
* Decimal Notation: 3911144.10337 (Block height + offset within block)
* Degree Notation: 3°254094′314″10497‴ (More on this shortly)
* Percentile Notation: 99.99980712060024% (Satoshi's position in total supply)
* Name: satoshi (An alphabetic encoding of the ordinal number)

Arbitrary assets like NFTs, security tokens, accounts, or stablecoins can utilize ordinal numbers as immutable identifiers attached to individual satoshis.

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