I have taught this topic for many years, and so my first thanks must go to my students, from whom I have learned so much. I am also grateful to former colleagues at Chalmers University and current colleagues at the Oxford Internet Institute (OII) for many great conversations. At the OII, they include Grant Blank, Eric Meyer, Jonathan Bright and Bill Dutton. Outside the OII, there are far too many to list, but I want to thank especially