To understand the pressing need for effective cybersecurity policies, consider first how much we rely on information technology. In 2010, there were nearly 332 million personal computers in use in the United States — one for every man, woman, and child, with 20 million or so left over. In addition to all those PCs, there were another 148 million enterprise servers, tablet computers, eReaders, and smartphones exchanging both mundane and highly sensitive information across public and private networks. In fact, we rely on information technology for almost everything we do as a society — from personal tasks, such as paying bills and finding our way to new places, to matters central to the public interest, such as operating nuclear power plants and the country’s electricity grid.