2000 January 26th
W3C issued official recommendations for the XHTML 1.0 specification. The Extensible HyperText Markup Language (XHTML) is a markup language for creating hypertext documents in an Internet environment. XHTML originated from an integration of XML and HTML and was divided into three versions: Strict, Transitional, and Frameset. According to W3C’s original plans, XHTML was supposed to be the successor to HTML, whose development was completed by version 4.01. However, in 2007, a new version of HTML started being developed, labeled HTML5.