T he communication between scientists and the public is changing. Major drivers of this change are the rapid evolution of the Internet, now in its web 2.0 version with an abundance of video-sharing websites, blogging platforms and social networks; the ubiquity of mobile devices; and the merging of individual and public communication. The new infrastructures allow nearly instantaneous access to information and make it much easier for communicators—both professionals and laypersons —to directly address a broad audience. Web-based services have broken down technical and economic barriers that, in the traditional communication system, have separated professional communicators from the largely passive audience of traditional print and broadcast media. This interactivity among the participants of online communication potentially transcends the traditional model of mass communication—by which the information is transmitted from a sender, that is, the scientists, via journalists to the audience. Here, we discuss what the new media may hold in store for scientists and their efforts to communicate with different publics. Not all forms of online communication are conceptually different from traditional media, though. For the typical news consumer, the difference between reading the print edition of a newspaper or accessing it online may be trivial. They may derive some added value from other readers’ responses or from information about how often an article was shared by Twitter or Facebook, but these are rather secondary aspects. It seems that the traditional media, such as newspapers and magazines, are easily integrated into the Internet: their content is frequently referenced in blogs, shared in social networks, included in socalled news aggregators, such as Google News, and turns up in search results. In addition, traditional media increasingly provide additional content online, notably multimedia content, and link to further information and interactivity, notably reader comments. Click rates, shares and other response measures provide instant feedback to professional communicators who, in the traditional media environment, had to rely on measures such as news-stand sales figures, letters to the editor and viewer ratings.