Nothing like the Web has ever happened in all of human history. The scale of its impact and the rate of its adoption are unparalleled. This is a great opportunity as well as an obligation. If we are to ensure the Web benefits the human race we must first do our best to understand it. The Web is the largest human information construct in history. The Web is transforming society. In order to understand what the Web is, engineer its future and ensure its social benefit we need a new interdisciplinary field that we call Web Science.