Penetration testing is a method of security testing that evaluates the security of networks and systems to identify weaknesses and vulnerabilities. It enhances an organization's security by discovering security vulnerabilities, testing security measures, and reducing the risk of potential attacks. The stages of penetration testing typically include information gathering, vulnerability assessment, exploitation of vulnerabilities, and post-penetration. Testers use a variety of tools and techniques at each stage to continuously challenge the security of networks and systems.