Tracing

Definitions

Tracing is an observability technique that records the end-to-end path of a request as it traverses services in a distributed system. A trace is composed of spans, each representing a single operation (an HTTP call, a database query, a queue publish) with timing data and metadata. Parent-child relationships between spans reveal how services call each other and where latency accumulates. Distributed tracing is essential for debugging microservice architectures where a single user request may touch dozens of services. Tools like Jaeger, Zipkin, and Grafana Tempo visualize traces as waterfall diagrams. OpenTelemetry provides a vendor-neutral SDK for instrumentation, and trace IDs propagated via HTTP headers correlate spans across services into one trace.
In plain English: Tracking a single request's journey through all the different services it touches, so you can see where time is spent or errors happen.
Example: "The trace showed the request spent 800ms in the payment service and only 20ms everywhere else — that's our bottleneck."