The contents of your zip file containing your deployment package. If you are using the web API directly, the contents of the zip file must be base64-encoded. If you are using the AWS SDKs or the AWS CLI, the SDKs or CLI will do the encoding for you. For more information about creating a .zip file, go to Execution Permissions (http://docs.aws.amazon.com/lambda/latest/dg/intro-permission-model.html#lambda-intro-execution-role.html) in the AWS Lambda Developer Guide.
ZipFile is automatically base64 encoded/decoded by the SDK.