A pentester, or penetration tester, is an individual who identifies security flaws within a network or system. They are often external consultants, authorized by a company to perform security audits on their IT ecosystem, and identify any potential cybersecurity risks. Normally, a pentester begins by conducting reconnaissance on their client’s systems, looking for any potential vulnerabilities. Then, they try to infiltrate the systems by exploiting these vulnerabilities, and eventually gain access to critical data.