<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<!--I've no idea what the above mumbo-jumbo means, but my xhtml/css book said to put it in there...-->
All this is used to help the web browser figure out what you are trying to do.
The doctype tag tells the browser what kind of HTML you use, in this case XHTML 1.0, and the Transitional kind. The two common XHTML types are Transitional (general purpose) and Strict (a minimal version with very few tags). Because the XHTML and HTML 4.01 (for example) markup differ this tag is needed to make sure the document is "parsed" correctly by the browser. Anology: This tag tells the gamer what game (say, D&D 3.5, Fallout) you use in your group. The gamer needs this information to play with you.
The xmlns-part of the regular HTML tag tells the browser what xml namespace is used. XML is a general purpose markup language and does not have to include the common tags such as head, body, a or strong. Anology: This tag tells the game system, such as d20. If you know you play a d20 game, you know you have reserved words such as AC, HP, STR etc, and that by STR you mean the d20 kind and not the kind you use in various programming languages.
The xml tag identifies the document as a xml document. XHTML is, after all, a XML document. Encoding tells the browser how to interpret weird characters, such as chinese letters. This tag tells the gamer you are playing a Role Playing Game, in English.
Hope that helps a little.
Edit: The above has nothing to do with XHTML and CSS itself, so dont worry too much about it. _You_ already know that you are creating a webpage using XHTML, but the browser does not.
You dont have to know this to design Great Webpages.
