> 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/1.-introduction.md).

# 1. Introduction

Casey Rodarmor's Ordinal Theory provided a special lens through which to view Bitcoin. It revealed individual satoshis (the smallest units of BTC) as unique digital objects. 

This made these satoshi-objects immutable collectors items, giving them similar properties and values to that of NFTs (Non-Fungible Tokens).

The community stretched Casey’s notion further, and quickly rendered entire token ecosystems from the Ordinals' breakthrough.

One such member, domo, even invented a way to create fungible “BRC-20” tokens, a token standard similar to Ethereum’s ERC-20.

While BRC-20s were an ingenious Ordinal-based fungible token prototype, they were created as an experiment and face significant limitations compared to their ERC-20 counterparts. 

This is where Runes come in. Also created by Casey, the **Runes Protocol** is an attempt to introduce a native, optimized implementation of a fungible token standard for Bitcoin.

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