Review the Evolution of HTML
To help you keep all the options in markup languages in perspective, here's a quick review of how we got to where we are now. The World Wide Web was built on good old HTML, the Hypertext Markup Language, which was born out of SGML, the Standard Generalized Markup Language, which dates all the way back to 1986.
XML, the eXtensible Markup Language, was also born out of SGML. XML caught on so well that it became a standard for sharing data across all kinds of documents and systems.
The popularity of XML led to the evolution of HTML to XHTML. Essentially, XHTML is a more restrictive subset of SGML, one that can be read better by XML parsers because it follows the rules strictly. If you can picture the typical odd couple, HTML is the sloppy roommate and XHTML keeps the contents of the medicine cabinet in alphabetical order.
This five-minute version of the history of HTML is only part of the story of how we got to where we are now. In what many now consider a misguided effort, the makers of the first mobile web browsers created another markup language, the Wireless Markup Language (WML). Perhaps an understandable reaction to the limited options of early feature phones, WML is now quickly being discarded.
And, you should note that the term Wireless Application Protocol (WAP) is used to describe everything related to the mobile web. WAP 1.0 represents the earliest attempts at mobile web design, including websites created with WML.
When the mobile web evolved to WAP 2.0 in 2002, most mobile devices could display pages designed in XHTML Basic (a subset of XHTML that has no support for CSS). Since 2004, most phones can handle XHTML MP, which (mostly) supports CSS 2.
C-HTML, another mobile markup language you may run into on the web, was designed to be used on NTT DOCOMO phones in Japan, but most mobile designers in Japan now predict that the iPhone’s growing popularity in Japan means that C-HTML will eventually be replaced by XHTML MP.
The good news is that all the code designed for the mobile world is based on good old HTML. So if you have a background in HTML, you’re off to a great start.
If you want to create a site that will work for any of the more than 6,000 devices in the market, you need a design strategy that includes all these languages and pages created and delivered to match each device.