Observability in Distributed Systems: Metrics, Logs, and Traces

Use metrics to locate a change, traces to follow affected work, and logs to inspect recorded events. This lesson combines those signals in a checkout investigation and explains what missing or sampled telemetry cannot tell you.

When a single user request travels through a dozen microservices, pinpointing the source of an error becomes a significant challenge.

Local debugging remains useful, but a request crossing services needs correlated evidence from several processes. Instrument the boundaries so you can connect a user-visible failure to the operations that contributed to it.

This lesson explores observability, the practice that enables engineers to understand a system’s internal state by examining its external outputs. It is the key to moving from reactive problem-solving to proactive system improvement.