ECS stands for Elastic Container Service. It is a fully managed container orchestration service provided by Amazon Web Services (AWS) that allows you to easily run, manage, and scale Docker containers on AWS infrastructure.

Key features and concepts of ECS include:

1. Container Orchestration: ECS automates the deployment, scaling, and management of containerized applications. It allows you to run Docker containers without managing the underlying servers or infrastructure manually.
2. Cluster Management: ECS organizes resources into clusters, which are groups of EC2 instances (virtual servers) or AWS Fargate instances that run your containers. ECS automatically handles scheduling and managing the resources within these clusters.
3. Task Definitions: In ECS, you define your containerized applications in "task definitions." A task definition is a blueprint that describes which Docker containers to run, their settings (e.g., CPU, memory), and how they interact with other services.
4. Service Management: ECS allows you to define services that ensure your containers run continuously, are scaled according to demand, and are replaced automatically if they fail.
5. Integration with Other AWS Services: ECS integrates with various AWS services like Elastic Load Balancer (ELB), CloudWatch for monitoring, IAM for security, and ECR for container image storage, enabling a seamless environment for deploying containerized applications.
6. Fargate: ECS can run containers on EC2 instances, but it also supports AWS Fargate, a serverless compute engine that removes the need to manage the underlying infrastructure. With Fargate, you only specify the CPU and memory requirements, and AWS handles the rest.
7. Scaling: ECS can scale applications automatically based on demand, ensuring that your containers are appropriately distributed across resources.