The advent of the Human Genome Project has transformed biology by providing a genetics parts list of all genes and proteins, by fueling the contention biology is an informational science, and by catalyzing the emergence of biological information (e.g., rapid DNA sequencing or DNA chips). From this has emerged a new approach to biology termed systems biology—centered on the idea one can study biological systems by delineating the relationships of all of their component elements—and, hence, come to understand the resulting systems properties. I will discuss these important points, give several examples of systems approaches, and conclude by discussing the profound change systems biology will engender in medicine—moving us toward a predictive, preventive, and personalized medicine.