The AWS Serverless Application Model (SAM) Transformer is a Python library that converts SAM templates into AWS CloudFormation templates. It serves as the core transformation engine for the AWS SAM CLI, enabling developers to define serverless applications using SAM syntax that gets expanded to standard CloudFormation resources. The system follows a modular architecture with distinct layers for parsing, validation, transformation, and resource generation, featuring an extensible plugin system for adding custom transformation logic. Key capabilities include intrinsic function resolution (!Ref, !GetAtt, !Sub), globals and conditions processing, policy template expansion, and resource-specific transformations for AWS services like Lambda, API Gateway, Step Functions, and more.