AMI selection based on:

• region/AZ
• OS
• ARCH (32/64)
• launch permissions
• storage for the root device:
  • instance store (ephemeral storage)
  • EBS backed volumes

Types

• EBS
  • root device is an Amazon EBS volume created from an Amazon EBS snapshot
  • can be stopped (without losing data)
• Instance Store
  • you cannot stop the instance
  • less durability than EBS
  • if underlying host fails, you will lose data

Important:

• by default root volumes will be deleted on termination
• but you can keep EBS volumes