The 8 Wastes expand the original seven muda categories from the Toyota Production System with an eighth — unused human talent. A common mnemonic is DOWNTIME: Defects, Overproduction, Waiting, Non-utilized talent, Transportation, Inventory, Motion, and Extra processing.
Learning to see the 8 wastes is the first practical skill in any lean transformation, because everything that is not value-added from the customer's perspective falls into one of these buckets. Overproduction is often called the worst waste because it hides and generates all the others.