What does penetration testing do?

Penetration testing or pen testing is a method to test software and hardware components in a safe, simulated environment to reveal the systems' vulnerabilities, bugs and flaws. The pen test must be legally authorised by the owner of the systems. Pen testing is an efficient tool for cybersecurity professionals to know what problems exist within a network, system or code. Once they know the problem and what risks it can cause, necessary steps are taken to fix it.

Deliberately putting a virus through the system to check if system is secure enough to detect and block it.