XHTML, or extensible hypertext markup langauge, is a new improved version of HTML. Improved because XHTML is stricter about coding using standards. HTML is quite relaxed by comparison. If all web developers start coding according to stricter standards, then the job of making browsers that behave nicely becomes easier.
Over the years, since the beginning of the web, people have developed websites with varying degrees of skill and care. As a result, there are many sites that have very sloppy code. These sites fail to work properly in the better, standards-based browsers. If you take the time to learn standards-based web development, you will be rewarded with a robust, fast, and multiple browser compatible website.
In case you haven't gone through the "Where to start" section of the website, we'll repeat some information here:
- * XHTML elements must be properly nested
- * XHTML elements must always be closed
- * Empty elements must also be closed, e.g. "<br>" becomes "<br / >"
- * XHTML elements must be in lowercase
- * An XHTML document must contain, as its first line, a DOCTYPE declaration
- * The <html> element must contain an xml name space
We suggest going through at least part of the "Where to start" lesson by jumping in at the page called "Coding an XHTML Page"