The transformative power of the Internet on all aspects of daily life, including health care, has been widely recognized. These transformations reveal opportunities realized, the promise of future advances, and the problems created by the penetration of the World Wide Web for both individuals and for society at large. Health Web Science explores the role of the Web as it drives discussions, technologies, policies, and solutions related to health. We also examine the impact of the Web–s health-related uses on the design, structure and evolution of the Web itself. The orientation of Health Web Science, compared to related research domains, motivates innovation in Web technology and better utilization of the Web for communication, collaboration, information access and sharing, remote sensing, and even remote treatment.