Book excerpt: An urgent warning from two bestselling security experts--and a gripping inside look at how governments, firms, and ordinary citizens can confront and contain the tyrants, hackers, and criminals bent on turning the digital realm into a war zone. "In the battle raging between offense and defense in cyberspace, Clarke and Knake have some important ideas about how we can avoid cyberwar for our country, prevent cybercrime against our companies, and in doing so, reduce resentment, division, and instability at home and abroad."--Bill Clinton There is much to fear in the dark corners of cyberspace: we have entered an age in which online threats carry real-world consequences. But we do not have to let autocrats and criminals run amok in the digital realm. We now know a great deal about how to make cyberspace far less dangerous--and about how to defend our security, economy, democracy, and privacy from cyber attack. Our guides to the fifth domain -- the Pentagon's term for cyberspace -- are two of America's top cybersecurity experts, seasoned practitioners who are as familiar with the White House Situation Room as they are with Fortune 500 boardrooms. Richard A. Clarke and Robert K. Knake offer a vivid, engrossing tour of the often unfamiliar terrain of cyberspace, introducing us to the scientists, executives, and public servants who have learned through hard experience how government agencies and private firms can fend off cyber threats. With a focus on solutions over scaremongering, and backed by decades of high-level experience in the White House and the private sector, The Fifth Domain delivers a riveting, agenda-setting insider look at what works in the struggle to avoid cyberwar.