It was December 17, 1996, when the World Wide Web Consortium (W3C) released the official W3C CSS Recommendation for the style sheet language that would be known as CSS1. CSS2 came less than two years later (May 1998), while its revised version, CSS2.1, took considerably more time (June 2011).

Starting from CSS3, things started to become more complex, since the W3C ditched the single, monolithic specification approach by splitting it into separate documents called modules, each one of them following its very own publishing, acceptance, and recommendation history. Starting in 2012, with four of these (Media Queries, Namespaces, Selectors, and Color) being published as formal recommendations and full CSS2.1 backward-compatibility, CSS3 quickly became the most adopted style sheet language standard for the development of new websites.