Amazon Machine Images or AMIs are pre-built virtual machine images that have the basic components for what is needed to start an EC2 instance. 
AMI Components
- Operating System
- Storage Setup
- Architecture Type
- Permissions for Launching
- Extra Software Installed
Three Ways to Use AMIs
- Create a custom AMI with specific configurations and software;
- Use pre-configured AWS AMIs; or
- Purchase AMIs from the AWS marketplace