Counter
In plain terms
A metric that only increases over time.
Going deeper
A counter tracks a cumulative count that only goes up (like total requests), reset only on restart. Rates are derived from its increase.
Under the hood
You compute rates from its delta over time; monotonic by design, unlike a gauge.
Examples
Request counts, error totals, bytes sent, Prometheus, rate calculations.
Think of it like...
Like an odometer that only ticks upward as you drive.