counter

A counter is a device, mechanism, or software construct that records the number of times a particular event occurs. Counters track occurrences, measure frequency, or maintain a running tally in settings ranging from clocks and odometers to digital circuits and software.

Mechanical counters are often manually operated, such as tally counters with rotating wheels. Odometers in vehicles and event counters in industrial equipment are other examples.

Electronic counters use digital logic and can count upward, downward, or both. They may be modulo n and include ripple (asynchronous) and synchronous variants. Applications include frequency division, timing, event counting, and data sampling.

In software, a counter is a numeric variable that records how many times an event occurs. Counters are incremented or decremented, used in loops and statistics. In multi-threaded environments, atomic or synchronized counters prevent race conditions.

Other uses of "counter" include linguistic counters or measure words in some languages, and terms like counterexample or counterargument in rhetoric.