Versions of XHTML

XHTML 1.0

The original XHTML W3C Recommendation, XHTML 1.0, was simply a reformulation of HTML 4.01 in XML. There are three different "DTDs" of XHTML 1.0, each equal in scope to their respective HTML 4.01 versions.
• XHTML 1.0 Strict is the same as HTML 4.01 Strict, but follows XML syntax rules.
• XHTML 1.0 Transitional is the same as HTML 4.01 Transitional, but follows XML syntax rules. It supports everything found in XHTML 1.0 Strict, but also permits the use of a number of elements and attributes that are judged presentational, in order to ease the transition from HTML 3.2 and earlier. These include center, u, strike, and applet.
• XHTML 1.0 Frameset: is the same as HTML 4.01 Frameset, but follows XML syntax rules. It allows the defining of an HTML frameset, a common practice in versions of HTML prior to HTML 4.