Forking is a mechanism of splitting in a community and is typically found in the free and open source software field. As a failure of cooperation in a context of open innovation, forking is a practical and informative subject of study. In-depth researches concerning the fork phenomenon are uncommon. We therefore conducted a detailed study of 26 forks from popular free and open source projects. We created fact sheets, highlighting the impact and motivations to fork. We particularly point to the fact that the desire for greater technical differentiation and problems of project governance are major sources of conflict.