Cyber security is vital in the modern age of computers. Modern society, economy and critical industrial infrastructures are greatly dependent on computer networks and other IT solutions. Mounting cyber attacks on them is both cheaper and less risky than attacks with armies and bombs. Military forces of the advanced nations and their computer wizards have turned the internet into the battle arena of the future. A couple of keystrokes could bring electric power grids, dams, airlines and banking to a grinding halt. Hackers could steal vital data from even your personal computer sitting thousands of miles away or could take complete control of it worse they could use it to launch a malicious attack the blame of which will fall on you.This is not science fiction. The Stuxnet virus unleashed by America and Israel damaged nearly 1000 of Iranian centrifuges and set back their nuclear program by at least five years--all without firing a single shot Cyber espionage malware like Duqu, Flame and Rocra have been quietly stealing secret information stored in computers of Defence aerospace and nuclear industries and sensitive government offices.This is the first comprehensive coverage of the subject in the world, ranging from computer security cyber security risks, the secrets of hacking and hacking into wireless networks, computer networks the Internet firewalls password hacking hacking of websites and databases and anti-hacking measures to cyber warfare capabilities of various nations.