“Pentest” is short for “penetration test”, and involves having a trusted security expert attack a system for the purpose of discovering, and repairing, security vulnerabilities before malicious attackers can exploit them. This is a critical procedure for securing a system, as the alternative method for discovering vulnerabilities is to wait for unknown agents to exploit them. By this time it is, of course, too late to do anything about them.

In order to keep a system secure, it is advisable to conduct a pentest on a regular basis, especially when new technology is added to the stack, or vulnerabilities are exposed in your current stack.