...You can find implementations of the specification by looking for packages providing the psr/simple-cache-implementation virtual package. Caching is a common way to improve the performance of any project, making caching libraries one of the most common features of many frameworks and libraries. Interoperability at this level means libraries can drop their own caching implementations and easily rely on the one given to them by the framework, or another dedicated cache library. PSR-6 solves this problem already, but in a rather formal and verbose way for what the most simple use cases need. ...