trace ID
also: request ID, correlation ID, transaction ID, X-Trace-ID, traceparent
A unique identifier assigned to a request or transaction as it flows through a system, allowing you to track and correlate related log entries and events across multiple services or processes.
A trace ID is a unique token generated at the entry point of a request and propagated through all downstream services, processes, and components that handle that request. It enables end-to-end visibility by linking together all log entries, spans, and events related to a single transaction.
In distributed systems and microservices architectures, a trace ID helps developers and operators understand the complete path a request takes. For example, when a web request arrives, a trace ID might be generated and passed along as the request flows through an API gateway, authentication service, database, and cache—allowing all related logs to be grouped and analyzed together.
Trace IDs are fundamental to distributed tracing systems like Jaeger, Zipkin, and OpenTelemetry. They are typically stored in HTTP headers (X-Trace-ID, traceparent) or request metadata and automatically logged by each component that processes the request.