AWS Lambda@Edge can be used to make decisions on how requests should be handled before they reach a CloudFront origin. A popular use case is origin selection for A/B testing, but it can also be used in a similar manner to provide custom content that is optimized for a particular device type or user region. Other use cases include user authentication through CloudFront (e.g., verifying user credentials when serving static assets) and some forms of fine-grained cache optimization.