With billions of computers in existence, cyberspace, ‘the virtual world created when they are connected,’ is said to be the new medium of power. Computer hackers operating from anywhere can enter cyberspace and take control of other people’s computers, stealing their information, corrupting their workings, and shutting them down. Modern societies and militaries, both pervaded by computers, are supposedly at risk. As Conquest in Cyberspace explains, however, information systems and information itself are too easily conflated, and persistent mastery over the former is difficult to achieve. The author also investigates how far ‘friendly conquest’ in cyberspace extends, such as the power to persuade users to adopt new points of view. He discusses the role of public policy in managing cyberspace conquests and shows how the Internet is becoming more ubiquitous and complex, such as in the use of artificial intelligence.