Red Teams and Blue Teams are different names given to security teams that work together to test and improve an organization's security posture. These terms have their origins in military training exercises, where they were used to refer to opposing teams in war games.
A Red Team is a team of offensive security professionals that are responsible for simulating real-world attacks on an organization's systems and networks. They use a variety of techniques, including penetration testing, social engineering, and other types of attacks, to identify vulnerabilities that could be exploited by real-world attackers.
A Blue Team is a team of defensive security professionals that are responsible for defending an organization's systems and networks against attacks. They use a variety of tools and techniques to monitor an organization's systems for signs of attack and to respond quickly to any security incidents that occur.
The military use of the terms Red Team and Blue Team dates back to the Cold War era, when the U.S. military began using war games and other training exercises to prepare for potential conflict with the Soviet Union. In these exercises, a Red Team would represent the Soviet Union or other opposing forces, while a Blue Team would represent the United States or other friendly forces.
The concepts of red teaming and blue teaming were later adopted by the cybersecurity industry as a way to describe different types of security testing and defense. The term purple teaming was also developed as a way to describe a collaborative approach to security testing and improvement.