AWS CloudFormation provisions AWS infrastructure as code. Templates in YAML or JSON define resources and configurations. Stacks are deployed collections of CloudFormation resources. Resources section defines AWS components like EC2, S3, RDS. Parameters accept input values for template customization. Mappings provide lookup tables for region-specific values. Conditions control resource creation based on parameters. Outputs return information about deployed resources. Intrinsic functions like Ref and Fn::GetAtt reference resource attributes. Pseudo parameters provide environment information. Change sets preview modifications before execution. Stack updates modify deployed resources with minimal disruption. Stack policies protect critical resources during . Nested stacks organize complex infrastructure. Drift detection identifies manual changes outside CloudFormation. Resource import brings existing resources under management. Custom resources extend CloudFormation with Lambda. Template validation catches syntax errors early. CloudFormation Designer provides visual template editor. CloudFormation ensures reproducible infrastructure deployments across environments.