Stack Overflow is considered a Collaboration platform (it says on the main page) but I am having some problem with that definition as I think this is actually a Cooperation platform.
Cooperation: Each actor helps the others to realize their goals by adjusting its policies in the anticipation of its own reward. Each actor is not necessarily out to help the other,though; it is the anticipation of bettering one's own situation that leads to the adjustment in one's policies. Milner, Helen. “International Theories of Cooperation Among Nations: Strengths and Weaknesses.” World Politics 44, no. 03 (1992): 466–496.
Collaboration is a process in which autonomous actors interact through formal and informal negotiation, jointly creating rules and structures governing their relationships and ways to act or decide on the issues that brought them together; it is a process involving shared norms and mutually beneficial interactions. A. M. Thomson and J. L. Perry, “Collaboration Processes: Inside the Black Box,” Public Administration Review, vol. 66, pp. 20–32, 2006