ECS (Amazon Elastic Container Service) is an orchestration service that runs Docker containers within the Amazon Web Services (AWS) cloud. It allows users to declare the components of a container-based infrastructure and ECS will deploy, maintain, and remove those components automatically. ECS integrates with other AWS services such as Elastic Load Balancing and Auto Scaling. The service reports resource metrics, including CPU and memory utilization, and provides key metrics for monitoring ECS status. Users can configure task definitions to reserve resources for entire tasks and individual containers, and ECS calculates resource metrics based on reservation and utilization. Monitoring ECS infrastructure is essential to ensure the availability and performance of applications running in the cloud.