A white hat is the hero or good guy, especially in computing slang, where it refers to an ethical hacker or penetration tester who focuses on securing and protecting IT systems.
White hat hackers are computer security experts, who specialize in penetration testing, and other testing methodologies, to ensure that a company's information systems are secure. White hat hackers are also called "sneakers", red teams, or tiger teams. These security experts may utilize a variety of methods to carry out their tests, including social engineering tactics, use of hacking tools, such as Metasploit, whichexploits known vulnerabilities, and attempts to evade security to gain entry into secured areas.
The National Security Agency offers certifications such as the CNSS 4011. Such a certification covers orderly, ethical hacking techniques and team management. Aggressor teams are called "red" teams. Defender teams are called "blue" teams.