What is a difference between a counter and a gauge?

The key difference between acounterand agaugein Prometheus lies in how their values change over time. Acounteris a cumulative metric thatonly increases—it resets to zero only when the process restarts. Counters are typically used for metrics like total requests served, bytes processed, or errors encountered. You can derive rates of change from counters using functions like rate() or increase() in PromQL.

Agauge, on the other hand, represents a metric that cango up and down. It measures values that fluctuate, such as CPU usage, memory consumption, temperature, or active session counts. Gauges provide a snapshot of current state rather than a cumulative total.

This distinction ensures proper interpretation of time-series trends and prevents misrepresentation of one-time or fluctuating values as cumulative metrics.