> For the complete documentation index, see [llms.txt](https://docs.billiondollarcat.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.billiondollarcat.com/bitcoin-runes.md).

# Bitcoin Runes

{% hint style="info" %}
tl;dr: Bitcoin Runes are fungible tokens on Bitcoin, similar to ERC-20 tokens on Ethereum.
{% endhint %}

## Overview

Runes are a protocol for fungible tokens on Bitcoin created by [Casey Rodarmor](https://x.com/rodarmor), who launched the Bitcoin Ordinals protocol for non-fungible tokens (NFTs) in early 2023. Runes are the next evolution of the BRC-20 fungible token standard originally built on top of Ordinals.

By using Bitcoin's UTXO model and the OP\_RETURN opcode, Runes improve Bitcoin's efficiency around fungible tokens as well as simplify their creation and management.

Similar to ERC-20 tokens on Ethereum, Runes can be used for different purposes. Currently, they're most often used for memecoins like Billy 😼

<details>

<summary>Bitcoin Ordinals &#x26; BRC-20</summary>

The Bitcoin Ordinals protocol enabled inscribing data, often images, onto individual satoshis on Bitcoin. This allowed for the creation of NFTs on Bitcoin.

BRC-20 is a fungible token standard built on top of Ordinals.

Runes were created to address some key inefficiencies with BRC-20s such as data bloat, incompatibility with Bitcoin Layer 2 solutions, and extra transactions to transfer BRC-20s.

</details>

## Details

**Want more?** Read the [Runes technical specifications](https://docs.ordinals.com/runes.html).