A visual management tool that allows the status of processes in a given area to be made clear at a glance and deviations to be understood. 

An andon can indicate production status (for example, which machines are in use), an anomaly (such as machine downtime, a quality problem, machining errors, operator-induced slowdowns and material shortages), and necessary actions, such as conversions. An andon can also be used to indicate production status in terms of the number of planned units versus actual output. 

A typical andon, which is the Japanese term for "lamp," is a board with rows of numbers corresponding to workstations or machines. A number lights up when a problem is detected. This is done either by a sensor, which automatically turns on the appropriate light, or by an operator, who pulls a cord or presses a button. The illuminated number requires a quick response from the team leader. Colored lighting on top of machines to indicate problems (red) or normal activity (green) is another type of andon.