Symfony 3.1 was the first version of the new Symfony3 family to offer new features. The first 3.0 release had feature parity with the last of the Symfony2 series. Symfony 3.1 was launched in May 2016, with a moderate list of added individual features, but one that was a big step in terms of caching: [an] implementation of the cache PSR (PSR-6). The new component is also automatically wired in FrameworkBundle and Symfony Standard Edition."
He talks about how following the PSR-6 standard allows for caching tools to only need to worry about the underlying implementation, not the interface. The post also talks about a new feature coming in Symfony 3.2 around caching: cache tagging. This allows you to "link" cache entries together using tags as related items. One potential use of this is invalidating cache records linked to a specific resource or page in the application without having to check each entry.