Final answer:
Amazon CloudWatch uses metrics to monitor AWS services and custom applications. Metrics are data points collected over time, which can be graphically represented and used to set alarms and trigger actions in other AWS services.
Step-by-step explanation:
Metrics in Amazon CloudWatch are used to monitor and collect data points on the performance of AWS services and applications. CloudWatch provides built-in metrics as well as the option of creating custom metrics to monitor specific aspects of your services. Metrics are recorded for a period, which can be from one minute up to one day.Metrics are the fundamental concept in CloudWatch and represent a time-ordered set of data points. They are identified by a name, namespace, and one or more dimensions. Dimensions are key-value pairs that uniquely identify a metric. For example, you might have a metric for CPU utilization on a particular EC2 instance, with the instance ID as the dimension.CloudWatch allows you to view graphical representations of metric data, set alarms based on threshold levels, and automatically make changes to the resources you are monitoring in response to those alarms.
Metrics data in CloudWatch can also trigger scaling policies for AWS Auto Scaling or workflows in AWS services such as AWS Lambda or Amazon S3.In Amazon CloudWatch, metrics are handled through the use of CloudWatch Alarms and CloudWatch Logs.CloudWatch Alarms allow you to monitor certain metrics and send notifications when those metrics breach predefined thresholds. For example, you can set up an alarm to send an email if the CPU usage of an Amazon EC2 instance exceeds a certain percentage.CloudWatch Logs, on the other hand, enable you to collect and monitor logs from your applications and resources. You can create metric filters to extract specific data from these logs and then use these metrics for monitoring.