Browser Wars and Cell Phones
During the 1990 Browser Wars between Microsoft and Netscape, each company tried to outdo the other with new features. It didn't take long before web developers discovered that they didn't need stop tags and it didn't seem to matter what order the tags were in.
Browsers kept getting bigger and bigger and they started doing all the work for the developers. The HTML code got sloppier and sloppier. But hey, who cared? Memory was getting cheaper, computers were doubling in speed every 18 months, and nobody (except Web instructors) seemed to care how the HTML code looked.
Then, along came PDA, cell phones, and handheld computers. These had tiny memories and couldn't handle the huge browser programs. The browsers written for these computers insisted on having code written in a precise manner.
At the same time XML (eXtensible Markup Language) was being developed at the W3C (World Wide Web Consortium) allowing businesses to create their own tags in documents so information could be easily exchanged between different types of computers.
XML has become widely adopted by the business community because it allows different companies (and their computers) to exchange information in a precise manner. The XML standard uses precise rules so everyone can understand the data without mistakes. (With XML if a single character is wrong the whole page is declared invalid!)
These XML rules were combined to HTML making a new specification named XHTML. Writing in XHTML will ensure that your pages will display with all browsers, both large and small.
As an added benefit, learning and using these few rules will also get you prepared for XML itself.
