An AMI provides all the software required to launch an instance including the following:

• The boot sectors and disk layout
• The operating system
• The cloud-init components to configure your instance at launch
• Default block device mappings that define the volumes to be attached to the instance
• Launch permissions controlling who can run the instance
• Any optional applications
• Custom images that include user data

You can use a pre-existing AMI provided by Amazon or partners on the Amazon marketplace to launch your instances so can create and register your own AMIs. The simplest way of creating your own AMI is to launch a new instance, customize it, and then save your instance as a custom AMI.

AMIs are always created within a region, so you can only run EC2 instances from a specific image with a specific image ID within any availability zone of a region. If you need to use the same AMI in multiple regions, you can copy the particular AMI over to another region. The AMI in the new region will receive a new AMI ID. You can then run the same configuration in another region by specifying the copied AMI during launch. When you no longer require an AMI, you can de-register it; this will essentially delete the AMI and remove it from AWS. It is a good practice to de-register your old AMIs as they are stored on S3 so you will be charged for the consumed resources: