The document discusses an empirical study of roles in open source software development projects. It finds that while developers contribute code, many open source projects also benefit greatly from non-coding roles like commenters, reviewers, and reactors. The study analyzed over 100 NPM package projects to determine the distribution of roles and how specialized communities are around each role. It was found that commenters have high activity levels and that non-coding roles become more important as projects grow. The diversity of roles in different projects and communities was also analyzed.