Kanban Explained: Visualize Work, Limit WIP and Improve Flow
How Kanban works for knowledge work: defining and visualizing a workflow, limiting work in progress, pulling work, and using flow metrics to improve.
The Agile Coach · Last reviewed October 21, 2026 · 5 min read
Kanban is often reduced to a board with sticky notes in columns labeled To Do, Doing and Done. The board is the most visible part, but it is not the point. Kanban is about how work flows from the moment someone starts it to the moment it delivers value, and about making that flow smoother and more predictable over time.
Unlike Scrum, Kanban has no fixed roles, Sprints or required meetings. That flexibility makes it easy to start and easy to do badly. A board without limits on work in progress can simply make an overloaded team's overload more visible.
This guide explains Kanban for knowledge work as described in the Kanban Guide, its roots in the Toyota Production System, and practical ways to put its ideas to work.
Where Kanban Comes From
The Japanese word kanban means "sign" or "signboard," according to the Lean Enterprise Institute's lexicon. In manufacturing, a kanban is a signaling device that authorizes the production or movement of items in a pull system. At Toyota, kanban cards were used so that parts were produced or moved only when a downstream step signaled that it needed them. Toyota describes Just-in-Time, a core idea of its production system, as making only what is needed, when it is needed, and in the amount needed.
The Kanban Guide traces the present state of Kanban to the Toyota Production System and its antecedents, and to the work of people like Taiichi Ohno and W. Edwards Deming. It says the collection of practices for knowledge work now commonly called Kanban mainly originated on a team at Corbis in 2006. Separately, Kanban University's guide to the Kanban Method states that the method is based on David J. Anderson's 2010 book on the subject.
There is more than one reference guide in the Kanban community. This article draws mainly on The Kanban Guide published at kanbanguides.org, whose current edition is dated May 2025 and credits John Coleman and Daniel Vacanti; it is licensed by Orderly Disruption Limited and Daniel S. Vacanti, Inc. Kanban University publishes The Official Guide to The Kanban Method, which adds change management principles such as starting with what you do now and pursuing improvement through evolutionary change, alongside six general practices that include visualizing, limiting WIP and managing flow. The two guides overlap heavily but use some different language.
The Core Idea: Optimizing Flow
The Kanban Guide defines Kanban as "a strategy for optimizing the flow of value through a process." Flow is the movement of potential value through a system. The guide frames the goal as finding the right balance of effectiveness (delivering what stakeholders want when they want it), efficiency (using resources well) and predictability (forecasting delivery within an acceptable degree of uncertainty).
According to the guide, Kanban comprises three practices working together:
- Defining and visualizing a workflow.
- Actively managing items in a workflow.
- Improving a workflow.
Defining and Visualizing the Workflow
Before a team can improve flow, it needs a shared understanding of what flow means in its context. The Kanban Guide calls this the Definition of Workflow. At a minimum it covers what a work item is, where work starts and finishes, the states work moves through, how work in progress will be controlled, explicit policies for how items move, and a service level expectation, which is a forecast of how long an item should take, such as 85 percent of items finishing in eight days or less.
The visualization of that definition is the Kanban board. The guide offers no required layout. A simple software team might use columns such as Ready, Developing, Reviewing, Testing and Done, but the right columns are whatever reflects the real workflow. A common early discovery is that work spends long periods waiting between states, which no one noticed until it was visible.
Limiting Work in Progress and Pulling Work
Work in progress (WIP) is the number of items that have started but not finished. The Kanban Guide requires teams to explicitly control WIP and notes that doing so should create a pull system: people start new work only when there is a clear signal of capacity, such as WIP dropping below the agreed limit.
This is the part of Kanban teams most often skip, and it matters most. Starting more work feels productive, but every started item competes for attention, and switching between items adds delay. Limiting WIP encourages people to finish things, and when a column is full, it encourages them to help clear a blockage rather than start something new.
Imagine a team of five with a WIP limit of three in its Reviewing column. Reviewing fills up, so a developer who has just finished coding cannot move another item in. Instead, she helps review. The queue clears, items reach Done sooner, and the team learns that code review is a bottleneck worth addressing.
Managing Flow with Metrics
The Kanban Guide names four flow metrics that every Kanban system should track:
- WIP: the number of work items started but not finished.
- Throughput: the number of work items finished per unit of time, counted exactly.
- Work Item Age: the time elapsed since an item started, for items still in progress.
- Cycle Time: the time elapsed between when an item started and when it finished.
Work Item Age is especially useful day to day. Comparing an item's age to the service level expectation shows which items are at risk of running late while there is still time to act. Throughput and cycle time history support forecasting, which our guide to estimation covers in more detail.
The guide is clear that these metrics are only meaningful if they inform the three practices. They are tools for the team's decisions, not scores for comparing teams.
Improving the Workflow
Improvement in Kanban is continuous. Many teams review their workflow at a regular cadence, but the Kanban Guide says there is no need to wait for a formal meeting, and improvements need not be small if a bigger change is warranted.
Practical places to start include:
- Making policies explicit, such as what Done means for each column.
- Lowering a WIP limit slightly and watching what happens to cycle time.
- Tracking why items get blocked and tackling the most common cause.
- Splitting large items so they flow through the system faster.
Key takeaways
- Kanban is a strategy for optimizing the flow of value, built on three practices: defining and visualizing a workflow, actively managing items, and improving the workflow.
- Its roots lie in the Toyota Production System; the Kanban Guide says the knowledge-work practices mainly originated at Corbis in 2006.
- Controlling work in progress is what turns a board into a pull system, and it is the step teams most often skip.
- WIP, throughput, work item age and cycle time are the four flow metrics in the Kanban Guide.
- There is no required board layout; the board should reflect the team's real workflow.
Sources
Spotted something out of date? Let us know.