A set of Google Cloud services for monitoring applications and infrastructure: Cloud Monitoring (metrics, dashboards, alerts, and SLOs), Cloud Logging (logs), Cloud Trace (distributed latency), and Cloud Profiler (code performance). It was formerly called Cloud Operations Suite and, before that, Stackdriver.
In CDL it is the foundation of SRE practices: measuring SLIs, defining SLOs, and alerting on error-budget burn. Question: get alerts when an application fails and analyze its logs → Cloud Monitoring and Cloud Logging, part of Google Cloud Observability.
Google Cloud Observability is a concept that can show up on the exam. Check the full guide to see it in context.