Introduction
Evolution and interactivity of online media
The Internet has profoundly changed the daily lives of hundreds of millions of people. It has increasingly provided users with virtually unlimited and rich content, as well as interactivity that offers users a high degree of control in their processing of this content (what information they see, for how long, how many times, and in what order; Nysveen & Breivik, 2005; Sterne, 2002). On the advertisers' side, the Internet has been increasingly considered as an attractive alternative to traditional media and obviously transformed the overall media space. Recent data even show that digital...