AMI is Amazon Machine Image, which basically is a copy of your root file system. It feeds the information required to launch an instance.
We implement AMI by specifying an AMI whenever we want to launch an instance. Multiple instances can be launched from a single AMI with the same configuration.
In the case of launching instances with different configurations, we would need to launch different AMIs.
AMI includes one or more snapshots of your EBS volumes, in the case of instance-store backed AMIs, along with a template for the root volume of your instance (like an operating system, an
application server, and applications).
It launches the permissions that decide which AWS accounts can use the AMI for launching instances. It also needs a block device mapping for specifying the volumes in order to attach them to the instances whenever they are launched.