Amazon's CloudWatch service provides a way to collect and monitor metrics and events from AWS resources, including EC2 instances. To access CloudWatch metrics, users can use the web console, the AWS command line tool, or a third-party monitoring service that integrates with the CloudWatch API. Additionally, users can supplement available CloudWatch metrics by running a monitoring agent that pulls system-level information not directly collected by CloudWatch. The service provides various options for filtering and aggregating data, including dimensions, periods, and statistics. Users can create dashboards to visualize multiple configurable graphs simultaneously and set alarms to notify them when certain thresholds are exceeded. The AWS CLI tool also allows users to query the full AWS API from the command line, enabling them to collect metrics and status checks programmatically. Furthermore, Amazon provides SDKs for major programming languages and mobile platforms to access the CloudWatch and EC2 namespaces via APIs. However, CloudWatch has limitations in terms of collecting resource metrics, such as memory usage statistics, which can be addressed using custom metrics or a comprehensive monitoring service like Datadog.