AMI: What OS and what software do you want on the instance?

Three AMI sources:

Provided by AWS

AWS Market Place: Online store for customized AMIs. Per hour billing

Customized AMIs: Created by you.

AMIs contain:

Root volume block storage (OS and applications)

Block device mappings for non-root volumes

Configure launch permissions on an AMI(Who can use the AMI?)

Share your AMIs with other AWS accounts

AMIs are stored in Amazon S3 (region specific)

Best Practice: Backup upto date AMIs in multiple regions

Critical for Disaster Recovery