The words you need to know

A way of running an organisation that focuses on delivering value to the customer while eliminating everything that doesn't contribute to it. Developed at Toyota, spread to manufacturing, then healthcare, software, and beyond. The core idea: less waste, more flow, continuous improvement. It's a philosophy as much as a set of tools.

The management system developed by Toyota after World War Two that became the foundation of lean thinking. Built on two pillars: just-in-time (produce only what's needed, when it's needed) and jidoka (stop and fix problems the moment they occur). Most of lean's vocabulary traces back here.

Anything a customer is willing to pay for. In lean, value is defined by the customer, not by the business. Everything in a process is either adding value or it isn't. Most processes, when mapped honestly, contain far more non-value-adding activity than anyone expected.

The full sequence of steps required to deliver a product or service to a customer, from raw material or first request through to delivery. Mapping the value stream shows you where value is added and where time, effort, and money are lost. You can't improve what you haven't seen.

Work moving smoothly through a process without interruption, delay, or waiting. The goal of lean is to create flow. When work stops: waiting for approval, queuing at a bottleneck, sitting in a pile. That is a failure of flow. The smoother the flow, the faster the delivery and the lower the cost.

A system where work is only started when the next step is ready to receive it. The opposite of push, where work is produced in advance and queued up. Pull systems reduce overproduction and make problems visible immediately. Kanban is a pull system. Most traditional manufacturing is push.

The Japanese word for waste, any activity that consumes resources without adding value for the customer. Toyota identified seven types: overproduction, waiting, transport, over-processing, inventory, motion, and defects. A common addition is unused talent. Learning to see muda is one of the most valuable skills in lean.

Overburden. Asking people or equipment to do more than they can sustainably handle. Muri leads to mistakes, breakdowns, and burnout. It's often invisible until things go wrong. Lean tries to design work so that overburden isn't required to hit targets.

Unevenness or variability in workload. Demand that surges and drops, batch processing that creates peaks and troughs, inconsistent work methods. Mura causes both waste and overburden. Levelling the workload (heijunka) is the solution.

Making more than the customer needs right now. Toyota considered it the worst of the seven wastes because it causes most of the others: excess inventory, unnecessary transport, wasted motion. In knowledge work, overproduction looks like reports nobody reads or features nobody uses.

Continuous improvement. Small, incremental changes made constantly, by everyone, at every level. Not occasional big projects. Not transformation programmes. Daily, habitual improvement by the people doing the work. The idea that no process is ever finished, and everyone is responsible for making it better.

A method for organising a workplace so that everything is in order, easy to find, and problems are visible. The five steps: Sort (remove what isn't needed), Set in order (a place for everything), Shine (clean and inspect), Standardise (make the standard the default), Sustain (keep it that way). Simple in principle, hard to maintain in practice.

A signalling system for managing the flow of work. In manufacturing, a physical card that triggers production or replenishment only when needed. In knowledge work, a board showing what's in progress, what's waiting, and what's done, with limits on how much can be in progress at once. The principle is the same: pull work, don't push it.

A visual tool for drawing out every step in a process, including the time spent waiting between steps. Reveals where the real delays are, which is almost never where people assume. The map of the current state is usually a surprise. The map of the future state is the improvement plan.

Error-proofing. Designing a process or product so that mistakes are impossible, or immediately obvious if they occur. A USB plug that only fits one way. A checklist that must be completed before a system will proceed. The goal: don't rely on people not making mistakes. Design the mistake out.

A visual signal, traditionally a light or cord on a production line, that alerts the team when something is wrong. Any worker can stop the line. In lean, stopping to fix a problem immediately is better than letting defects pass through. In knowledge work, an andon is anything that makes a problem visible the moment it occurs.

Levelling the production schedule to smooth out peaks and troughs. Instead of processing orders in big batches when they arrive, work is spread evenly over time. Reduces overburden on people and equipment, reduces inventory, and makes the system more predictable. One of the harder lean concepts to implement.

Producing and delivering exactly what is needed, exactly when it is needed, in exactly the right quantity. No stockpiling, no overproduction. Reduces inventory costs and makes problems visible immediately, if a supplier is late, you know straight away. Requires very reliable supply chains to work.

The rate at which you need to complete work to meet customer demand. If customers want 100 units a day and you work 500 minutes a day, your takt time is 5 minutes per unit. Takt time sets the rhythm of production. Working faster creates overproduction. Working slower creates a backlog.

How long it actually takes to complete one unit of work from start to finish. If cycle time is longer than takt time, you can't meet demand. Comparing cycle time to takt time tells you where the process needs work.

The total time from a customer placing an order to receiving it. Includes all the waiting, queuing, and processing. Lean tries to reduce lead time by eliminating the non-value-adding time. Most lead time is waiting, not working.

A measure of how productively a machine or process is being used compared to its theoretical maximum. Combines availability (is it running?), performance (is it running at full speed?), and quality (is it producing good output?). 100% OEE is perfect production. Most operations are somewhere between 40% and 85%.

The place where the work actually happens. The factory floor, the ward, the warehouse, the call centre. In lean, management is expected to go to the gemba to understand what's really going on, not rely on reports and dashboards. "Go to the gemba" is a challenge to leaders who manage from a distance.

A structured visit to the place where work happens, with the specific purpose of observing, asking questions, and understanding the current state. Not an inspection. Not a performance review. A genuine attempt to see the work as it is, not as it is reported to be.

The documented best current method for performing a task. Not a rigid rule, but a baseline. If everyone does the work differently, you can't identify what good looks like or where problems come from. Standard work makes variation visible. It's also the starting point for improvement, you can only improve something you have defined.

Finding the underlying cause of a problem, not just fixing the symptom. Lean uses the "5 Whys" method: ask why five times and you'll usually reach the real cause. The machine broke. Why? Because it wasn't maintained. Why? Because there was no schedule. Why? Because no one owned it. Fix the ownership problem, not the machine.

The improvement cycle at the heart of lean. Plan: identify the problem and design a solution. Do: test it on a small scale. Check: measure whether it worked. Act: if it worked, standardise it. If it didn't, learn from it and start again. Also called the Deming cycle. Simple in structure, demanding in practice.