Review Stacks, powered by Pulumi Deployments, are automated cloud environments that are created whenever a pull request is opened, facilitating streamlined development and testing processes. These environments allow developers to iterate on both application and infrastructure code simultaneously, supporting technologies from static websites to complex systems like Kubernetes clusters. When a pull request is merged, the environment is automatically dismantled, optimizing cloud costs by eliminating the need for perpetual infrastructure. The integration with GitHub allows for seamless collaboration and review, while the ability to configure Review Stacks through various Pulumi tools and APIs simplifies deployment management. This innovation enhances development velocity and efficiency by standardizing development environments and change management, making it easier for developers to handle multiple projects and feature branches. Pulumi's approach enables engineers to independently manage infrastructure changes, reducing reliance on dedicated infrastructure teams and facilitating faster project delivery.