This document provides an introduction to cyber security. It defines cyber security as protecting cyberspace from attacks, and defines a cyber attack. It tells how much it is important to know about cybersecurity. It explains that cyberspace us where online communication occurs, via the internet. Cyber security is important because it affects everyone who uses computer and networks. So, to protect our information and data from unauthorized access we must know about cyber attacks and its preventions, also about the future of cyber security.