Ethical hacking refers to the act of locating weaknesses and vulnerabilities of computer and information systems by duplicating the intent and actions of malicious hackers. This act is performed by computer and network expert known as Ethical hacker. An ethical hacker operates with the knowledge and permission of the organization for which they are trying to defend. Ethical hacking is also known as penetration testing, intrusion testing and red teaming. First examples of ethical hackers at work was in the 1970s, when the United States government used groups of experts called red teams to hack its own computer systems.