Amazon EC2 AMI lifecycle
An Amazon Machine Image (AMI) is an image that provides the software that is required to set up and boot an instance. You must specify an AMI when you launch an instance.
Amazon provides AMIs that you can use to launch your instances, or you can create your own AMIs. For example, you can launch an instance from an existing AMI, customize the instance (for example, install software and configure operating system settings), and then save this updated environment as a new AMI. Any instance customizations are saved to the AMI, so that the instances that you launch from your new AMI include these customizations.
You can use an AMI only in the AWS Region in which it was created. If you need to launch instances with the same configuration in multiple Regions, you can create an AMI in one Region and then copy your AMI to additional Regions.
To prevent an instance from being used temporarily, you can disable the AMI. After you disable an AMI, you can't use it to launch new instances. After you enable the AMI, you can use it to launch instances again. Note that deregistering an AMI does not affect the instances that you already launched from the AMI.
When you no longer require an AMI, you can deregister it. After you deregister an AMI, you can't use it to launch new instances. Note that deregistering an AMI does not affect the instances that you already launched from the AMI.
You can use Amazon Data Lifecycle Manager to automate the creation, retention, copy, deprecation, and deregistration of Amazon EBS-backed AMIs and their backing snapshots. For more information, see Amazon Data Lifecycle Manager.