Dictionary

Observability is the ability to understand the internal state of a system by examining its external outputs — primarily logs, metrics, and traces (the "three pillars"). Unlike basic monitoring that checks predefined thresholds, observability enables you to ask arbitrary questions about system behavior and debug novel issues. Tools like Grafana, Datadog, and OpenTelemetry provide automated collection and correlation of telemetry data across distributed services.

Optimistic UI is a pattern where the interface immediately reflects the expected result of a user action before the server confirms it. For example, a "like" button instantly shows the liked state while the API request happens in the background. This makes the app feel significantly faster and more responsive. If the server request fails, the UI rolls back to the previous state and notifies the user.

Orchestration is the automated coordination of multiple services, tasks, or systems to execute a complex workflow. An orchestrator acts as a central controller that manages the sequence, parallelism, error handling, and retries of individual steps. In the context of AI agents, orchestration involves chaining LLM calls, tool use, and decision-making steps; in DevOps, it coordinates container deployment, scaling, and service discovery.