The "5 Whys" is a problem-solving technique used to explore the cause-and-effect relationships underlying a particular problem. Its primary goal is to determine the root cause of a defect or problem by repeating the question "Why?" five times. Each answer forms the basis of the next question. In the context of SAFe 6 Release Train Engineer, the 5 Whys are utilized within the Lean-Agile principles to drive relentless improvement by identifying the root causes of impediments and issues that may be affecting the Agile Release Train's (ART) performance. This method helps in creating a culture of transparency and continuous improvement, which is essential for the successful execution of SAFe1.