Waste is the second key concept of Lean. It is the opposite of value: anything that we do not want or a result that has no worth. Eliminating waste is at the root of most, if not all, Lean processes.

In his book Toyota Production System, Taiichi Ohno says, “In production, ‘waste’ refers to all elements of production that only increase cost without adding value – for example, excess people, inventory, and equipment.”