> ## Documentation Index > Fetch the complete documentation index at: https://docs.openlit.io/llms.txt > Use this file to discover all available pages before exploring further. # What is AI Observability? > AI observability explained: what it is, why it matters, and how to add it to LLM apps and agents with zero code changes AI observability is the practice of collecting traces, metrics, and logs from LLM applications and AI agents so you can see exactly what happened on every request - which model was called, how long it took, what it cost, and whether it failed. ## Why does AI observability matter? LLM applications fail in ways traditional monitoring doesn't catch: a model can return a slow, expensive, or low-quality response without ever throwing an error. Without AI observability, you only find out from a user complaint. With it, you can see the exact prompt, model, latency, and cost behind every call - and catch regressions before they reach production. ## What data does AI observability cover? * **Traces**: the full request flow - model calls, tool calls, retries, and agent steps, in order. * **Metrics**: aggregated numbers over time, like latency, token throughput, and error rate. * **Logs**: discrete events emitted by your application and its dependencies. * **Cost and token usage**: spend per request, model, and provider, computed from token counts and per-model pricing. ## How is AI observability different from traditional APM? Traditional application performance monitoring (APM) tracks HTTP requests, database queries, and infrastructure health. AI observability adds what APM tools don't understand: which model and provider handled a call, the prompt and completion content, token usage, per-call cost, and the tool-call graph an agent followed to produce its answer. ## How does OpenLIT provide AI observability? OpenLIT auto-instruments 90+ LLMs, agent frameworks, and vector databases via OpenTelemetry - with zero code changes - and surfaces traces, metrics, and logs in one [Telemetry](/latest/openlit/observability/telemetry/overview) page, plus a trace-derived call graph for every [agent](/latest/openlit/observability/agents/overview) it observes. *** View traces, metrics, logs, and exceptions in one place See every agent's trace-derived call graph, tools, and versions Instrument an LLM app with zero code changes in 2 steps