Operating time counters are devices used to monitor and record the runtime of machines, equipment, or processes. They typically feature a simple interface, often equipped with LCD or LED displays that show the accumulated time in hours or minutes. Some models offer relay or open collector (OC) outputs, enabling basic control functions. These timers are used to track work cycles and schedule maintenance and service intervals. They help optimize machine performance and extend equipment lifespan.

A separate family of counters involves time-meters, such as chronographs, clocks etc. The most commonly used group comprises simple or more complicated controllers.