Kanban is a tool derived from lean manufacturing and is associated with the branch of agile practices loosely referred to as Lean Software Development. Like a task board, Kanban visually represents the state of work in process. Unlike a task board, the Kanban constrains how much work in process is permitted to occur at the same time. The purpose of limiting work in process is to reduce bottlenecks and increase throughput by optimizing that segment of the value stream that is the subject of the Kanban. A principle difference between Kanban and Scrum is that Scrum limits work in process through timeboxing (i.e. the sprint) and Kanban limits work in process by limiting how much work may occur at one time (e.g. N tasks or N stories).