Software code that is publicly accessible, meaning that anyone can view, modify and redistribute the code. The mission of open-source software is to promote openness, transparency, collaboration and participation by anyone in the development of the software. In relation to blockchains, many of the top blockchains are developed using open source software, with no central bank, government, or institution controlling the software.
Example
“Ethereum's open-source codebase on GitHub has thousands of contributors worldwide, enabling anyone to review smart contract logic and propose protocol upgrades.”