Observability

How trace sampling affects production debugging, including head sampling, parent-based sampling, tail sampling trade-offs, error traces, rare paths, async work, and metrics that show whether sampling is hiding incidents.

How correlation IDs in microservices connect logs, traces, queues, and background jobs across service boundaries without pretending to replace real tracing or metrics.

Observability vs logging in production, with a practical guide to when logs, metrics, traces, and correlation IDs answer different debugging questions.

A practical OpenTelemetry guide for backend engineers: what to instrument first, how traces, metrics, logs, context propagation, attributes, sampling, and collectors make production debugging clearer.