It is best practice to manage your AWS environment using CloudFormation for all new resources, and for all subsequent changes to these resources. If you sidestep CloudFormation, and make a manual change to a resource, then the template and the actual resource have drifted. Drift can cause all manner of problems when you go to make changes to the CloudFormation stack in the future.
In this recipe, you will learn about a new feature of CloudFormation—drift detection.