XHTML is a hybrid of HTML (Hypertext Markup Language) and XML (eXtensible Markup Language). But all you need to know is XHTML is a slightly cleaner more powerful version of regular HTML, so when you hear references to XHTML or HTML it’s basically referring to the same thing: the code used to write web pages.
This web page is written in XHTML. To understand how this works, imagine you have an article, with a headline, several paragraphs of text, an image and a link to another web page. In order to make this content display as a web page you need to surround each of the different parts with the correct HTML ‘tags’. So the headline would go between heading tags, for example like this:
Now, because you’ve put those ‘h1′ tags around the headline, browsers like Internet Explorer and Firefox will interpret the content between the tags as a heading and thus display it larger than paragraph text and on it’s own line.
The same applies with paragraphs, images and so forth. Without surrounding the content with the various tags, the content will just display like this:
Headlineparagraphlinktext
This is a very simple explanation of HTML. There is a lot more you can do with it. But hopefully this gives you the idea.
How do you make this HTML look good?
You might think that by adding lots of tags and images you can make your web pages look nice just using HTML. That is possible to some extent, but really, in order to make an HTML web page look nice you need to style it with CSS.