Glossary term
What is RED (Rate, Errors, Duration)?
RED stands for Rate, Errors, Duration.
In System Design
Key metrics for request-driven services. Example: 500 req/s, 0.2% errors, p99 180 ms.
Learn it properly · System DesignLesson 46: Logs, Metrics & Traces: The Three Pillars“Checkout took 20 seconds and failed” — but checkout touches eleven components. How logs, metrics and traces each answer a different question, how to instrument with OpenTelemetry, and how linking them takes you from “something's wrong” to “here's why” in minutes.In Backend in Depth
Three numbers to watch for every service: how many requests, how many fail, and how long they take (as percentiles).
Learn it properly · Backend in DepthLesson 5: Logging and Observability: Structured Logs, Correlation IDs, MetricsJSON logs, log levels, request IDs that follow a request through every service, and what you must never log.