The Industrial Internet is an emerging software and communication infrastructure that interconnects machines and data to build intelligent machines and applications never before possible. Using embedded sensors and software, machines connected via the Industrial Internet have the analytical intelligence to self-diagnose and self-correct, so they can operate reliably, react to real-world changes in their environment and provide more sophisticated service to their users. This white paper, written by Douglas Schmidt, Professor of Computer Science at Vanderbilt University, discusses the Industrial Internet in depth, including terminology, history, research, advances and challenges.