Since CDC acquired its first mainframe computer in 1964, the use of information technology in public health practice has grown steadily and, during the past 2 decades, dramatically. Public health informatics (PHI) arrived on the scene during the 1990s after medical informatics (intersecting information technology, medicine, and health care) and bioinformatics (intersecting mathematics, statistics, computer science, and molecular biology). Similarly, PHI merged the disciplines of information science and computer science to public health practice, research, and learning. Using strategies and Standards, practitioners employ PHI tools and training to maximize health impacts at local, state, and national levels. They develop and deploy information technology solutions that provide accurate, timely, and secure information to guide public health action.