Network penetration testing, or ethical hacking, assesses a computer network's security by identifying and exploiting vulnerabilities to simulate real-world attacks. The process includes stages such as planning, information gathering, vulnerability assessment, exploitation, and reporting, with various testing types like black box, white box, and grey box testing to cater to specific needs. The benefits include identifying overlooked vulnerabilities, testing security controls, meeting compliance requirements, and enhancing incident response, ultimately aimed at improving an organization's security posture.