BRC-20 is an experimental fungible token standard created to explore the possibility of using ordinal inscriptions on the Bitcoin blockchain to store immutable data and develop semi-fungible tokens natively. Initiated by an anonymous developer named domo in March 2023, BRC-20 leverages the concept of ordinal theory, which assigns unique numbers to individual satoshis, allowing various data types to be inscribed onto them. Unlike Ethereum's ERC-20 tokens that rely on smart contracts, BRC-20 tokens embed JSON data into ordinal inscriptions, enabling users to deploy, mint, and transfer tokens without altering the Bitcoin protocol. Although still in its experimental phase, BRC-20 has generated significant interest within the Bitcoin community, with infrastructure providers starting to integrate it into their services. However, the creator acknowledges that BRC-20 is not necessarily the definitive standard for fungibility on Bitcoin, and the open-source nature of the project leaves room for further innovation and optimization by the developer community.