Why do volunteers work on free software projects?

When asked, many claim they do it because they want to produce good software, or want to be personally involved in fixing the bugs that matter to them. But these reasons are usually not the whole story. After all, could you imagine a volunteer staying with a project even if no one ever said a word in appreciation of his work, or listened to him in discussions? Of course not. Clearly, people spend time on free software for reasons beyond just an abstract desire to produce good code. Understanding volunteers’ true motivations will help you arrange things so as to attract and keep them. The desire to produce good software may be among those motivations, along with the challenge and educational value of working on hard problems. But humans also have a built-in desire to work with other humans, and to give and earn respect through cooperative activities. Groups engaged in cooperative activities must evolve norms of behavior such that status is acquired and kept through actions that help the group’s goals.

— Karl Fogel, Producing Open Source Software