Pentesting is a security assessment, analysis and a progression of simulated attacks on an application or network to check its security posture. Its objective is to penetrate an organization’s security defenses by actively seeking out vulnerabilities. The vulnerabilities uncovered can then be used to fine-tune security policies, patch applications or networks and identify common weaknesses across applications. Pentesting can fortify organizations’ general security posture, full stop, and is a critical measure for organizations to put in place proactively to prevent security breaches.
Source: https://www.helpnetsecurity.com/2021/04/29/what-pentesting-is/