Spot Instances are instances that use spare EC2 capacity that is available for up to 90% off the On-Demand price. Because Spot Instances can be interrupted by EC2 with two minutes of notification when EC2 needs the capacity back, you can use them for applications that have flexible start and end times, or that can withstand interruptions5. This option is most cost-effective for the use case described in the question. Reserved Instances are instances that you purchase for a one-year or three-year term, and pay a lower hourly rate compared to On-Demand Instances. This option is suitable for applications that have steady state or predictable usage. Dedicated Instances are instances that run on hardware that’s dedicated to a single customer within an Amazon VPC. This option is suitable for applications that have stringent regulatory or compliance requirements. On-Demand Instances are instances that you pay for by the second, with no long-term commitments or upfront payments. This option is suitable for applications that have unpredictable or intermittent workloads.