A WIP (work in progress) limit caps how many items can be in a stage of a Kanban board at once, so the team finishes work before starting more.
When a column reaches its limit, nobody pulls new work into it; instead people help finish what is already there. This exposes bottlenecks and shortens cycle time, because work spends less time waiting.
Choosing a limit
A common starting point is one or two items per person in a stage, adjusted after a few weeks. If the limit is never hit it is too high; if work constantly stalls it may be too low.
Example
A support team sets a limit of 4 on "In review". When the column is full, developers review tickets before picking up new ones.
In Starlex
Starlex boards make work in progress easy to see with columns, swimlanes and filters by assignee. See Starlex boards.