Content Delivery Networks (CDN) help bring your content closer to your users all over the world. One key way the CDN improves latency is by intelligently caching files on CDN edge servers located in various geographic regions. This new feature allows customers using Azure CDN standard from Verizon or Akamai to create rules to direct the CDN servers to override their default caching behavior. Azure CDN from Premium customers would still be able to use the Rules Engine to manage their cache.
This feature will allow you to specify cache duration of a specific file, files under a path, or specific file extensions to be cached based on values specified to the CDN. Many users find this easier than managing cache directive headers on the origin server itself.
Read about it in the Azure blog.