Communities too sometimes use gamification techniques to boost participation. The Avaazwebsite, for example, exhibits a continually updated ticker listing the latest people to sign a petition,together with the total number of signatories, so that contributors feel they participate in anefficient, globally advancing movement. A more sophisticated example is Stack Overflow, acollaboratively edited question and answer site—initially about programming problems, but laterextended via Stack Exchange to a network of sister sites covering such diverse topics as cooking,physics, photography and language (Mamykina, Manoim, Mittal, Hripcsak, & Hartmann, 2011).Participants in these communities can ask questions, propose answers, and vote on the questionsand answers from other participants. As members contribute more good questions and answers andreceive more positive votes, their status as recognized “experts” increases via a point system. Thisallows them to reach increasingly advanced levels of privileges, so that the more active andconstructive contributors can make changes in the site organization that are impossible fornewcomers. Thus, every member has a continuing incentive to provide high-quality contributions,making the community remarkably fast and effective in dealing with its problems (Mamykina et al.,2011).