5s - Derived from Japanese words (Seiri, Seiton, Seison, Seiketsu, and Shitsuke) as part of the Toyota Production System (Lean Manufacturing). For this reason the 5 words used in english often vary.
5s allows for quick and easy visual control. It makes it obvious if things are missing or out of place which makes operations more efficient.
Jamie Flinchbaugh, Planning 5s? First Know Why!: "The true purpose of 5S is to spot problems quickly" and to correct them.