As applications run in production, you’ll need to find out what’s happening. You might want to know if you’re overloading the hardware, moving to the wrong feature in an A/B test, or, on the mobile side, even such simple contingencies as whether the battery is running out.
Developing an app to send information about itself means adding instrumentation. Apps can send such telemetry as metrics, logs, and traces to allow teams to interpret the internal state of the application. This concept is the basis of collection in observability.
Standardizing the collection and format of these signals is in large part the goal of the OpenTelemetry (OTel) project. An added benefit is, if most applications in a given language need to observe the same types of operations and workflows, developers building on the OTel standard can identify and build auto-instrumentation to do the work for them!