Explanation: After you create an AMI, you can keep it private so that only you can use it, or you can share it with a specified list of AWS accounts. You can also make your custom AMI public so that the communi-ty can use it. Building a safe, secure, usable AMI for public consumption is a fairly straightforward process, if you follow a few simple guidelines. Reference:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AMIs.html