A penetration tester, often referred to as an ethical hacker, identifies and exploits vulnerabilities in systems to strengthen security. The journey typically begins with learning about different types of security threats and vulnerabilities. Aspiring pentesters should develop skills in scripting and programming languages like Python, and gain proficiency with tools used for scanning, testing, and exploiting vulnerabilities. Ethical hacking certifications like OSCP (Offensive Security Certified Professional) can be valuable credentials in this field.