This document discusses ethical hacking. It defines hacking as unauthorized use of computer and network resources, and describes different types of hackers such as black hat, white hat, and grey hat. It then defines ethical hacking as a methodology used by trusted professionals to discover vulnerabilities in information systems. The document outlines skills required of an ethical hacker such as knowledge of operating systems, networking protocols, and security tools. It describes the steps an ethical hacker takes including reconnaissance, scanning, gaining access, and clearing tracks. Finally, it discusses advantages like improving security, and disadvantages like potential misuse of access.