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OpenTelemetry defines three signals of telemetry: traces, metrics, and logs. One specification and SDK produce all three in a consistent way.

Traces capture the path of a request across services as a tree of spans, answering where time went and what failed.

Metrics are numeric measurements aggregated over time: counters, gauges, and histograms that answer how much and how often.

Logs are timestamped records of discrete events. In OTel they can be correlated with traces by carrying the same trace and span IDs.

A Resource describes the entity producing telemetry, such as a service or host. It is attached to all three signals so they share identity.

All signals can carry the same context. A log and a metric exemplar can point back to the trace that produced them, enabling correlation.

Semantic conventions are agreed names for common attributes. Everyone uses http.request.method instead of inventing their own key.

Standard names let any backend understand your data. Dashboards, alerts, and tools work out of the box because the keys are predictable.

• Portability across vendors
• Reusable dashboards
• Automatic correlation

Conventions cover HTTP, databases, messaging, and more.

Resource attributes describe the producer and rarely change. Span attributes describe a single operation and vary per request.

Combining the three signals with shared resources and conventions gives full observability: metrics show what is wrong, traces show where, and logs show why.

You learned the three OTel signals (traces, metrics, logs), how a shared Resource and context tie them together, and how semantic conventions standardize attribute names for portability and correlation across any backend.