If you've ever been to a different part of your country than where you're from, you've probably noticed how the folks there talk, well, a little funny. They use different words or they say them with a different accent. And yet, you understand them just fine even if you chuckle about it in the car afterwards. That's the way it is with HTML and XHTML. In their case, they share precisely the same vocabulary (to the letter) but have a slightly different syntax.
Since they are so similar, I'll teach you HTML and XHTML at the same time. I'll start by explaining the syntax differences that distinguish them. And then throughout the book I will explain the vocabulary that they share. In those explanations, I use the stricter XHTML syntax (Figure i.1). You can either use it as is (to write XHTML), or opt for the looser HTML syntax (to write HTML). It's up to you.
Figure i.1. On many pages, you'll find a snippet of XHTML code, with the pertinent sections highlighted in blue.
It would be tiresome to have to refer to HTML and XHTML all the time, so I have chosen to use the abbreviated (X)HTML to refer to both at once. In the few instances I use one of the individual names, you'll know that the information pertains to that language only and not to the other.
CSS is incorporated into the descriptions of (X)HTMLagain, that means, both HTML and XHTMLas a natural extension and yet a separate tool. While the information about CSS is concentrated in Chapters 714, you'll find bits and pieces throughout the book, next to the part of (X)HTML to which it is most applicable (Figure i.2).
Figure i.2. If the CSS code is relevant to the example, it is shown in its own box, again with the pertinent sections highlighted in blue.
In this book, I have included illustrations from the major browsers on both Windows and Mac (Figure i.3). While you may stick with one browser, there's no telling what your visitors will use. I recommend getting used to how other browsers show (X)HTML.
Figure i.3. The XHTML and CSS are then displayed in one or more browsers so you can see how it looks in real life. (This example is from page 264.)