Most of us have gone online to search for information about health. What are the symptoms of a migraine? How effective is this drug? Where can I find more resources for cancer patients? Could I have an STD? Am I fat? A Pew survey reports more than 80 percent of American internet users have logged on to ask questions like these. But what if the digital traces left by our searches could show doctors and medical researchers something new and interesting? What if the data generated by our searches could reveal information about health that would be difficult to gather in other ways? In this book, Elad Yom-Tov argues that internet data could change the way medical research is done, supplementing traditional tools to provide insights not otherwise available.