We have all heard of HTML. HTML stands for Hypertext Markup Language. What is a hypertext markup language, you ask? It is a language for specifying how certain text should appear. When you design a web page, you want certain content or text to be displayed in a specific way. You may want some text to appear in bold or italics, while other text you may want to display larger or in color.
HTML is not the only type of markup language. There are markup languages that apply to other types of applications, such as word processing or other software applications. However, HTML was by far the most important markup language ever created, as it became the standard for displaying information on what is now known as the world wide web, or internet.
However, HTML is not the only markup language being used on the internet today. Another, better version of HTML evolved as programmers began to realize that HTML was innately flawed in a variety of ways.
By 1999, a new specification was written in a language called XML, which forms the basis for XHTML. The World Wide Web Consortium says the following about XHTML:
The Extensible HyperText Markup Language (XHTML) is a family of current and future document types and modules that reproduce, subset, and extend HTML, reformulated in XML. XHTML family document types are all XML-based, and ultimately are designed to work in conjunction with XML-based user agents. XHTML is the successor of HTML, and a series of specifications has been developed for XHTML
XHTML is what is known as a meta-language, which is a language for defining a markup language. To put it simply, SGML (Standard Generalized Markup Language) is the basis for HTML. XML is a more refined subset of SGML, and forms the basis for XHTML. On the whole, XHTML allows for more flexibility than HTML.
XHTML was developed for two reasons: (1) to try to create a language that could more effectively convey the meaning of a particular webpage to a computer, and (2) to create a layout for webpages that would be universally understood by browsers running on different platforms or on different types of screens, whether it be a PC platform with a standard 800 X 600 monitor, a laptop, a cell phone, or any other device.
So, to all you web designers out there, it is probably time to start designing your most important web pages in XHTML. As almost every electronic device on the market is now equipped with internet access, it is important to use a versatile programming language like XHTML so that your web pages can be viewed and properly formatted across a wide variety of platforms.