Amazon EC2 Spot Instances let you take advantage of unused EC2 capacity available in the AWS cloud. Spot Instances are available at up to a 90% discount compared to On-Demand prices. You can use Spot Instances for various stateless, fault-tolerant, or flexible applications such as big data, containerized workloads, CI/CD, web servers, high-performance computing (HPC), and other test & development workloads. Spot Instances are easy to launch, scale and manage through AWS services like Amazon ECS and Amazon EMR, or integrated third parties like Terraform and Jenkins.

Spot Instances can be launched via RunInstances API with a single additional parameter. You can also provision compute capacity across Spot Instances, RIs and On-Demand instances to optimize performance and cost using EC2 Fleet and Spot Fleet APIs. Spot Instances launched via these APIs are same as any EC2 instance; they provide the reliability, security, performance, control, and elasticity of Amazon EC2, at low market-driven prices. Spot Instances are now available in the AWS GovCloud (US-West) Region. To learn more about Amazon EC2 Spot Instances, visit our documentation.

AWS GovCloud (US) is Amazon’s isolated cloud infrastructure and services designed to address specific regulatory and compliance requirements of US Government agencies, as well as contractors, educational institutions, and other US customers that run sensitive workloads in the cloud. Visit AWS GovCloud (US) homepage to learn more about these regions.

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/06/amazon-ec2-spot-now-available-in-the-aws-govcloud-us-west-region/