What AWS service can be used for real-time monitoring and alerts?

Amazon CloudWatch is the service designed specifically for real-time monitoring and alerts within the AWS ecosystem. It provides you with insights into your AWS resources and applications by collecting and tracking metrics, collecting log files, and setting alarms.

With CloudWatch, you can set up custom alarms that trigger notifications based on specific metrics, such as CPU utilization or error rates, allowing you to respond promptly to changes in the status of your applications or infrastructure. This capability is crucial for maintaining the health and performance of applications running in the cloud.

The other services mentioned, while useful in their own right, do not focus primarily on real-time monitoring. Amazon S3 is used for object storage, AWS Lambda is designed for running code in response to events, and AWS CodeDeploy automates code deployments. Each of these services plays a different role in a cloud environment, but CloudWatch is the primary tool for monitoring and alerting.