title: Why there are both counters and gauges in Prometheus if gauges can act as counters?
body: <p>When deciding between <code>Counter</code> and <code>Gauge</code>, <a href="https://prometheus.io/docs/practices/instrumentation/#counter-vs-gauge-summary-vs-histogram" rel="noreferrer">Prometheus documentation states that</a></p>
  
  <blockquote>
    <p>To pick between counter and gauge, there is a simple rule of thumb: if
    the value can go down, it is a gauge. Counters can only go up (and
    reset, such as when a process restarts).</p>
  </blockquote>
  
  <p>They seem to cover overlapping use cases: you could use a Gauge that only ever increases. So why even create the Counter metric type in the first place? Why don't you simply use Gauges for both?</p>