Open source software is everywhere. From phones, tablets, TVs, and game consoles to less self-evident examples like cars, washing machines, and the International Space Station. However, what makes open source software remarkable is not where it can be found, but rather what can be done with it. One of the most astounding rights guaranteed by all open source software licenses is the right to fork the source code. In other words, the right to copy any program, either in part or in its entirety, and use that program to create a new, modified version of it. The right to fork has an enormous impact on both the development and governance of open source software. Despite its significance, code forking has seen little academic study. This dissertation examines the right to fork, its impact and significance, and how it is viewed and practiced by developers. The study draws on data consisting of hundreds of forks, interviews with open source software programmers, and an in-depth analysis of the birth of the MariaDB fork. This dissertation is relevant to anyone seeking a greater general understanding of how open source works and why it is considered a superior software development model. It may also serve as a useful resource for firms seeking to harness the power of open source software. Furthermore, it offers important insights to those who want to better understand how code forking is practiced and viewed by developers. This study finds that forks are primarily started for non-competitive reasons, with unique features or goals that distinguish them from their parent projects. Competitive forks are rare but do exist, with some motivating factors being to ensure the freedom of the code and the community’s ability to contribute to it. Furthermore, though developers may not always agree with the forking of a project, they nonetheless consider the right to fork to be of vital importance, and a cornerstone of free and open source software. In many ways, open source can be thought of as a return to how software was developed before the emergence of proprietary licensing. The same freedoms of development and sharing that thrived back then can be found today in the open source community. Indeed, in many ways the right to fork is synonymous with freedom: the freedom to explore and experiment, the freedom to benefit from the work done by others, and the freedom to keep any project relevant and vibrant even when faced with leadership decisions that are deemed unsupportable. In short, the right to fork is open source software’s guardian of freedom and watchdog of meritocracy.