Single-Minute Exchange of Die — shigeo-shingo's systematic methodology for reducing machine changeover times from hours to minutes (single digits). SMED has three stages: (1) separate internal setup (requires machine stopped) from external setup (can be done while machine runs), (2) convert internal setup to external where possible, (3) streamline all remaining operations. At Toyota, Shingo reduced a 1,000-ton press changeover from 4 hours to 3 minutes. This is not just a time-saving technique — it is the enabler of small batch production. When changeover is expensive (hours of downtime), economic logic demands large batches. When changeover is nearly free (minutes), small batches become efficient, enabling one-piece-flow and just-in-time. SMED is the manufacturing precursor to continuous deployment in software — the principle that reducing the cost of releasing makes frequent releasing rational. Described in a-revolution-in-manufacturing-the-smed-system.