A penetration test, colloquially known as a pen test, is an authorized simulated attack on computer systems, network, applications and IT assets. It's a step further to the vulnerability scan wherein the vulnerabilities discovered during the vulnerability assessment scan phase are exploited/penetrated to gain access into the target systems and sensitive data.

Its prime function is to look for any security weaknesses that could result in a malicious attacker potentially gaining access to the system's features or a weakness that could lead to inadvertent leakage of confidential information.