What is XHTML?
XHTML or Extensible Hypertext Markup Language is a “stricter” form of HTML and is actually an application of XML (Extensible Markup Language) which complements HTML by adding more functionality to the codes. While HTML is more concerned with how a webpage looks like, XML complements it by taking care of data transport and/or storage. But unlike XML where a programmer can set his own rules in making codes, XHTML requires exact rules for coding. In simple terms, XHTML is considered to combine the display flexibility features of HTML and the data management and extensibility of XML.
A great feature for XHTML is that it no longer has the previous problem with basic HTML in terms of webpage display on different browsers. With HTML alone, one page may display correctly on a particular browser but the same page may not be properly displayed using another browser. In the past, webpage developers needed to re-write codes for specific browsers just to make the necessary adjustments on display. With XHTML, marking up the existing code is made simple and easy.
The latest version of HTML which is 4.01 has similar features with XHTML version 1.0. And though the W3C endorsed XHTML as part of its official recommendations, many webpage authors still question the development of XHTML when both HTML and XML already exists. There was also a question with regards to XHTML’s compatibility with several webpage browsers. Because of the differences in the tags and coding, some browsers are not able to handle and display web page items properly.
But despite some resistance from various groups, the development of XHTML continued over the years. Upgrades to the initial version included XHTML 1.1, XHTML Basic and Mobile Profile that are able to support constrained devices and mobile phones, XHTML 1.2, and XHTML 2.0 which has less backward compatibility with HTML 4 browsers.