Policy as Code in Pulumi 2.0 enables developers and operators to automate deployment, test resources, and maintain version control using Python, making it a versatile tool for various applications including machine learning, web development, and DevOps. This approach offers significant benefits such as cost savings, enhanced compliance, and efficient deployment by allowing organizations to enforce specific resource criteria through policies, which can be either advisory or mandatory. Pulumi supports two types of policies: ResourceValidationPolicy, which checks individual resources before they are created or modified, and StackValidationPolicy, which assesses all resources in a stack after deployment. These policies are validated during previews and updates to prevent non-compliant resources from being deployed. Examples provided demonstrate the use of Python to create validation functions that enforce policies such as prohibiting public-read access on AWS S3 buckets or Azure Storage Containers, and ensuring Kubernetes services are not exposed as public LoadBalancers, showcasing how Policy as Code can build secure and efficient cloud infrastructures.