Amazon CloudWatch is a service that you can use to monitor your AWS resources and your applications in real time. With Amazon CloudWatch, you can collect and track metrics, create alarms that send notifications, and make changes to the resources being monitored based on rules you define.
Basic monitoring sends data points to Amazon CloudWatch every five minutes for a limited number of preselected metrics at no charge.
Detailed monitoring sends data points to Amazon CloudWatch every minute and allows data aggregation for an additional charge.
Amazon CloudWatch does not aggregate data across regions but can aggregate across Availability Zones within a region.