[albertmorrison3]

HTML4 became a W3C Recommendation in 1997. While it continues to serve as a rough guide to many of the core features of HTML, it does not provide enough information to build implementations that interoperate with each other and, more importantly, with a critical mass of deployed content. HTML has been in continuous evolution since it was introduced to the Internet in the early 1990's. Some features were introduced in specifications; others were introduced in software releases. The same goes for XHTML1, which defines an XML serialization for HTML4, and DOM Level 2 HTML, which defines JavaScript APIs for both HTML and XHTML.