What is 5 Porquês?

The "5 Whys" is an iterative interrogative technique used to explore the cause-and-effect relationships underlying a particular problem. The primary goal is to determine the root cause of a defect or problem by repeatedly asking the question "Why?". Each answer forms the basis of the next question. The "5" in the name derives from an anecdotal observation on the number of iterations needed to resolve the problem.