Difference between specification and recommendation that introduced CSS

The CSS Working Group creates documents called specifications. When a specification has been discussed and officially ratified by W3C members, it becomes a recommendation.

These ratified specifications are called recommendations because the W3C has no control over the actual implementation of the language. Independent companies and organizations create that software.

The World Wide Web Consortium or W3C is a group that makes recommendations about how the Internet works and how it should evolve.