The safe days of walled gardens are over. People collaborate on web sites, and as a return, the action of the individuals produces something new, even unexpected results. The emergence may be profitable business and provide income for firms, but it also impacts on the social relations and the lives of individuals. In this book, Katri Lietsala and Esa Sirkkunen describe the great variety of practices within the social media. They suggest some general principles how the traditional media could deal with the new situation and show with the help of their case studies what motivates people to participate. The book includes also a short introduction to the Finnish social media history.