Types

Reserved Instances

• Standard Reserved Instances
  • Apply to a single instance family, platform, scope, and tenancy over a term
  • One or three year term
  • Can reserve capacity (locked into one availability zone) or be regional (can launch in any AZ within the region)

• Convertible Reserved Instances
  
  • Can be exchanged for Convertible Reserved Instances with different instance families, platform, tenancy, or scope during the term
  • Three year term
  • Can reserve capacity (locked into one availability zone) or be regional (can launch in any AZ within the region)

Scheduled Instances

• One year term
• Repeating schedule (daily, weekly, monthly)
• http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-scheduled-instances.html

Tenancy

• If you're using dedicated instances, choose Dedicated Tenancy
• If not, choose Default Tenancy

Usage

Instance Size Flexibility

• All Regional Linux/UNIX RIs with shared tenancy now apply to all sizes of instances within an instance family and AWS region, even if you are using them across multiple accounts via Consolidated Billing.