Assets are local files or directories which can be bundled into CDK constructs and apps. A common example is a directory which contains the handler code for an AWS Lambda function, but assets can represent any artifact that is needed for the app’s operation.
When deploying an AWS CDK app that includes constructs with assets, the toolkit will first upload all the assets to S3, and only then deploy the stacks. The S3 locations of the uploaded assets will be passed in as CloudFormation Parameters to the relevant stacks.
For more details, see the :py:doc:`Assets <refs/_aws-cdk_assets>` library documentation.