Limit WIP - Create a Smooth Continuous Flow of Work

"Limiting work in progress (WIP) is perhaps the principle most closely identified with Kanban. The idea of WIP limits is to try to ensure that you never start or complete a task that cannot be passed smoothly on to the next stage without blocking up the ‘factory line’. To do this means having a ‘pull system’ rather than a ‘push system’ and is intended to create a smooth continuous flow of work down the line. How do you know what limits to set? Should you limit per person, per work item, or another way? How do you start and how can you use WIP limits to improve over time?"