Abstract: Cyber security is a dimension in the world of Internet revolution, where rapid increase in cyber-crimes and cyber-warfare is occurring to a level where national and international economy and security is at stake and destabilizing. Cyber-security, in short, is the protection from unauthorized access of data over the Internet and the prevention of exploitation of hardware and software vulnerabilities. Various strategies, techniques, models and frameworks have been established to address the issue of cyber security This paper gives an overview of various cyber threats, its related concepts and principles, effects of cyber-attacks on individual, national and global level, the models, frameworks and steps taken to cater cyber security, with there limitations and recommendations for improvements in cyber security measures.