In its 4th edition, this book remains focused on increasing public awareness of the nature and motives of cyber vandalism and cybercriminals, the weaknesses inherent in cyberspace infrastructure, and the means available to protect ourselves and our society. This new edition aims to integrate security education and awareness with discussions of morality and ethics. The reader will gain an understanding of how the security of information in general and of computer networks in particular, on which our national critical infrastructure and, indeed, our lives depend, is based squarely on the individuals who build the hardware and design and develop the software that run the networks that store our vital information. Addressing security issues with ever-growing social networks are two new chapters: Security of Mobile Systems and Security in the Cloud Infrastructure.