Explanation:
Penetration testing, often referred to as pen testing, is a security assessment technique where ethical hackers simulate cyberattacks to identify vulnerabilities in a system, network, or application.

The process involves planning, information gathering, vulnerability scanning, exploitation, and reporting. Pen testers attempt to exploit identified weaknesses to assess the security posture of the target environment.

Penetration testing can be black-box (no prior knowledge), white-box (full knowledge), or gray-box (partial knowledge) depending on the scope and objectives.

Additional Information:
Pen testing helps organizations proactively identify and fix security gaps before malicious actors can exploit them. Common tools used in penetration testing include Metasploit, Nmap, and Burp Suite.

Compliance standards such as PCI DSS often require regular penetration testing for organizations handling sensitive information. Reports from pen tests guide security improvements and risk mitigation strategies.

Formal Definition:
Penetration testing is a security assessment technique where ethical hackers simulate attacks on a system, application, or network to identify and exploit vulnerabilities, thereby evaluating its security posture.