Pulumi is an Infrastructure-as-Code (IaC) platform that lets you define cloud infrastructure using general-purpose programming languages (Python, TypeScript, Go, C#) instead of configuration languages like YAML or HCL. You write code that describes your infrastructure (servers, databases, networks, Kubernetes clusters), run pulumi up, and Pulumi provisions the actual resources in your cloud provider (AWS, Azure, GCP, etc.). Key benefits: code reuse, abstraction, type safety, and the full power of a programming language for defining complex infrastructure.