Table of Contents 1. What Is Observability in LLMs? A Detailed Overview A simple mental model Basic example 2. The Pillars of Observability 2.1 Logs: The Narrative 2.2 Metrics: The Health Indicators 2.3 Traces: The Story Across Services 2.4 New Pillars for LLMs: Evals & Feedback 3. Why Do We Need Observability for LLMs? 3.1 LLMs Fail Differently 3.2 Regulatory and Brand Risk 3.3 Cost and Performance 4. Why LLM Observability Matters at Scale 4.1 More Features, More Surprises 4