Few years back only there was a fire blazing to use HTML code for designing websites. Its presentation was later on succeeded by CSS. CSS used style sheets for the purposes. These definitely improved the materialization and appearance of all the websites. Today, HTML has been further improvised to XHTML.
XHTML is a more stable, sharpened and sophisticated version. This further introduced the concept of tagging into the websites. While going through modern version, most Word Press themes have been designed on XHTML rather then HTML. With the use of XHTML done in bulk across the web, it is imperative for users, who are designing, changing or preparing their themes, to know the difference between XHTML & HTML. These differences might even help in knowing the different validation errors, which usually arise from improper XHTML usage.