5 Whys is a root-cause technique where you ask “why?” repeatedly — typically around five times — until you get from the symptom to the underlying cause that can be removed, so the problem doesn’t return.
Example: the machine stopped → why? The fuse blew → why? The bearing ran hot → why? Insufficient lubrication → why? The lubrication routine was skipped → why? There is no standard for it. The root cause is a missing standard — not a blown fuse.
The pitfall is stopping at a person (“the operator forgot”). Ask one more time: why could it be forgotten? The answer almost always points to the system — a missing standard, training or mistake-proofing.