# Lambda version control
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Like all software, maintaining versioning enables the quick visibility of previously functioning code as well as the ability to revert back to a previous version if a new deployment is unsuccessful. AWS Lambda allows you to [publish one or more immutable versions for individual Lambda functions](https://docs.aws.amazon.com/lambda/latest/dg/configuration-versions.html) such that previous versions cannot be changed. Each Lambda function version has a unique Amazon Resource Name (ARN) and new version changes are auditable as they are recorded in [AWS CloudTrail](https://aws.amazon.com/cloudtrail/). As a best practice in production, customers should enable versioning to use a reliable architecture. 

 To simplify deployment operations and reduce the risk of error, [Lambda function aliases](https://docs.aws.amazon.com/lambda/latest/dg/configuration-aliases.html) activate different variations of your Lambda function in your development workflow, such as development, beta, and production. An example of this is when an [API Gateway](https://aws.amazon.com/api-gateway/) integration with Lambda points to the ARN of a production alias. The production alias will point to a Lambda version. The value of this technique is that it activates a safe deployment when promoting a new version to the live environment because the Lambda alias within the caller configuration remains static, thus there are fewer changes to make.