An Amazon Machine Image (AMI) is a template containing the software configuration (operating system, application server, and applications) required to launch an Amazon EC2 instance. You cannot launch an EC2 instance without specifying one.

• Every EC2 instance, whether one or thousands, starts as a clone of the selected AMI.
• Every AMI packages a root volume template, launch permissions, and a block device mapping.
• AMIs exist in a single AWS Region and must be explicitly copied to be used in another.
• AMIs are created, registered, copied, and deregistered. Deregistering does not automatically delete the underlying EBS snapshot.
• AMIs come from Amazon, the AWS Marketplace, the community, or your own custom build