AWS CloudFormation is Amazon's infrastructure as code (IaC) service for provisioning and managing AWS resources through declarative templates. Templates written in JSON or YAML define the desired state of resources, and CloudFormation handles creation, updates, and dependency management automatically. Unlike imperative scripting, CloudFormation's declarative approach lets you specify what infrastructure you need rather than how to build it, with built-in rollback on failure and drift detection to ensure your deployed resources match the template definition. Understanding intrinsic functions, conditions, and stack lifecycle management is essential for building production-grade, reusable infrastructure templates.