The hypertext visionaries foresaw the potential of richly interlinked global information systems for advancing human knowledge. The Web provided the infrastructure to enable those ideas to become a reality, and it quickly became a platform for collaborative research and data sharing. As the Web has evolved, new ways of using it for eResearch have emerged, such as the social networking facilities enabled by Web 2.0 technologies. The next generation of the Web-the so-called Semantic Web--is now on the horizon, which will again enable new types of collaborative research to emerge. If we are to understand and anticipate these new modes of collaboration, we need a discipline that studies the Web as a whole. Web science is this discipline.