In addition to On-Demand, Reserved Instances, and Savings Plans, the fourth Amazon Elastic Compute Cloud (Amazon EC2) pricing model is Spot Instances.
With Spot Instances, you can use spare Amazon EC2 computing capacity at discounts of up to 90% compared to On-Demand pricing. That means you can significantly reduce the cost of running your applications, or grow your application’s compute capacity and throughput for the same budget. The only difference between On-Demand Instances and Spot Instances is that Spot Instances can be interrupted by EC2 with two minutes of notification when EC2 needs the capacity back.
Unlike Reserved Instances or Savings Plans, Spot Instances do not require a commitment in order to achieve cost savings over On-Demand pricing. However, because Spot Instances can be terminated by EC2 if there is no available capacity in the capacity pool (a combination of an instance type and an Availability Zone) in which they are running, they are best suited for flexible workloads.
