CloudWatch is an essential tool for the DevOps engineer. CloudWatch supports the DevOps tasks of automation, communication, and collaboration by providing access to monitoring and logging tools. CloudWatch metrics work with Elastic Load Balancers and can be used to determine the scaling actions of Auto Scaling groups. Custom metrics are a very powerful tool, allowing the DevOps engineer to leverage CloudWatch monitoring in a wide range of scenarios. This lesson introduces all of these concepts before each is covered in further detail later in the section.