Counter`1 Represents an instrument that supports adding non-negative values. For example, you might call counter.Add(1) each time a request is processed to track the total number of requests. Most metric viewers display counters using a rate (requests/sec), by default, but can also display a cumulative total.

 Histogram`1 Represents a metrics instrument that can be used to report arbitrary values that are likely to be statistically meaningful, for example, the request duration. Call to create a Histogram object.

 Meter Meter is the class responsible for creating and tracking the Instruments.

 MeterListener MeterListener is class used to listen to the metrics instrument measurements recording.

 ObservableCounter`1 Represents a metrics-observable instrument that reports monotonically increasing values when the instrument is being observed, for example, CPU time (for different processes, threads, user mode, or kernel mode). Call to create the observable counter object.

 ObservableGauge`1 Represents an observable instrument that reports non-additive values when the instrument is being observed, for example, the current room temperature. Call to create the observable counter object.

 ObservableUpDownCounter`1

 UpDownCounter`1

 Measurement`1 Stores one observed metrics value and its associated tags. This type is used by an Observable instrument's Observe() method when reporting current measurements. with the associated tags.

 Instrument Base class of all Metrics Instrument classes

 Instrument`1 The base class for all non-observable instruments.

 ObservableInstrument`1 ObservableInstrument{T} is the base class from which all metrics observable instruments will inherit from.