This book extends the presentation of overview of the cyber security today, its common perception that cybersecurity is an issue of urgent national concern. Numerous aspects of cyberspace are well-known for being open to an increasing number of attacks from a variety of hackers, criminals, terrorists, and state actors. For instance, major and small private-sector businesses as well as government organizations experience sensitive information being stolen online, websites being defaced, and denial-of-service assaults. Information technology plays a significant role in the running of the nation's key infrastructure, which includes the electric power grid, air traffic control system, financial systems, and communication networks.