Web application penetration testing (pentesting) is a method of assessing the security of a web application by simulating real-world attacks. It involves identifying vulnerabilities, exploiting them, and providing recommendations for remediation. Common techniques used in web application pentesting include SQL injection, cross-site scripting (XSS), cross-site request forgery (CSRF), and more. The goal is to identify and address security weaknesses before they can be exploited by malicious actors.