What is Lean Software Development (Seven Wastes)?
Lean software development (the Poppendiecks' translation of Toyota principles) centers on eliminating waste — the seven: partially done work, extra features, relearning, handoffs, task switching, delays, defects — plus amplifying learning, deciding late, delivering fast, and respecting people.
The sharpest lens is "partially done work": code written but not deployed is inventory — cost incurred, zero value delivered, and rotting. Lean's answer to almost everything is: shrink batches, finish things.
Worked example
An audit of a fintech team finds: 14 features "done" but undeployed for a quarter (inventory), every story crossing three specialist handoffs, and developers juggling four projects (task switching). Lean surgery — deploy weekly, form one cross-functional team, WIP limit of two — and throughput doubles without anyone typing faster.