Google Cloud's serverless platform for running containers in response to HTTP requests or events. There's no infrastructure to manage; it automatically scales to zero when there's no traffic.
In CDL it's the serverless solution for containers. Difference from Cloud Run functions (formerly Cloud Functions): a Cloud Run service runs a container; functions deploys just the code of one function. Difference from GKE: Cloud Run doesn't require managing clusters.
Cloud Run is a concept that can show up on the exam. Check the full guide to see it in context.