OpenTelemetry: One Instrumentation Model For Traces, Metrics, And Logs

**OpenTelemetry (OTel)** is a CNCF project specifying APIs, SDKs, and the **OTLP** protocol for telemetry. It supersedes OpenTracing/OpenCensus for new instrumentation. Docs and specs live on `opentelemetry.io`.

**Traces** model requests as spans with parent/child relationships. **Metrics** are aggregated measurements (histograms, counters). **Logs** integrate through the logs bridge and semantic conventions.

Instrument at service boundaries first: HTTP handlers, database calls, message publish/consume. Use **context propagation** (W3C Trace Context) across services.

OTel is vendor-neutral; you choose exporters (Jaeger, Prometheus, Datadog, Honeycomb, etc.). Sampling strategies matter at high QPS: tail sampling captures interesting traces without storing everything.