An Amazon Managed Instance (AMI) is an image of the entire virtual machine. It acts as a template to provide the information required to launch an instance.
5 things you can base your AMI on:
When launching an EC2 instance, you must select an AMI to choose its configuration.
It is possible to create your own AMI using an existing AMI as a base.
AMIs are backed by either EBS or Instance store.
Instance store volumes are sometimes called ephemeral storage. They cannot be stopped, and if they underlying host fails, you will lose your data. If you delete hte instance, you will store the instance store volume.
EBS volumes can be stopped. By default they will be deleted on instance termination, but can be kept.
Both types can be rebooted.