# Bitcoin Runes
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tl;dr: Bitcoin Runes are fungible tokens on Bitcoin, similar to ERC-20 tokens on Ethereum.
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## 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 😼
Bitcoin Ordinals & BRC-20
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
**Want more?** Read the [Runes technical specifications](https://docs.ordinals.com/runes.html).
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