Maybe I am a fool however i don't quite get what gets into the header of my HTML to make use of XHTML w/ HTML5. Is still good and that we just add the HTML5 tags?:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html dir="ltr" lang="eng" xmlns="http://www.w3.org/1999/xhtml">

Or perhaps is it <!DOCTYPE html> or what?

Then at A Listing Apart they are saying:

Should you choose opt for XHTML 5, keep in mind that your server must provide the documents having a MIME kind of application/xhtml+xml or text/xml.

Please show me as though I had been stupid :) what which means inside a practical sense? "provide the documents"? Meaning html? What goes on to php? Do you know the steps needed to setup your internet server by doing this?

To properly serve HTML5 document, it's not necessary to do anything whatsoever unusual. Servers default to content-type right for HTML5. Just start your documents with:

<!DOCTYPE html>
<meta charset=UTF-8>

(meta isn't strictly necessary, but it's wise for doing things, otherwise you can find Home windows 1250 encoding or something like that worse).

Only serving of XHTML5 requires extra hoops to leap through. You need to send Content-Type: application/xhtml+xml header. There's not a way to get it done from inside document with any type of DOCTYPE or <meta>. It absolutely needs to be out-of-document HTTP header. How to achieve that is dependent on server/language you utilize. In PHP you'd do:

header("Content-Type:application/xhtml+xml;charset=UTF-8");

However, you most likely don't wish to do this, because IE does not support XHTML5 whatsoever. Stay with HTML5, that has far better compatibility with legacy UAs.

XHTML5 standard isn't written yet, so would like you want isn't achievable. Furthermore, HTML5 and XHTML 1. will vary unrelated standards of HTML.

The mime-type informs the consumer-agent how you can process the present resource. That's diverse from the doctype declaration, which informs the consumer-agent what the phrase the present resource is. The mime-type for SGML based HTML is text/html. SGML types of HTML include: HTML 4, HTML 5, XHTML 1., and all sorts of earlier versions of HTML. XML types of HTML should be processed using the application/xml+html mime-type that is just for XHTML 1.1 and XHTML 5.

The greatest variations between your SGML form and also the XML form is sloppiness. The SGML form is basically a text document and it is typically regarded as as tag soup where validation is frequently irrelevant and browsers attempt to perform the best they are able to. Within the XML form any error at any time within the code may cause the document to fail in the user-agent and throw a mistake towards the screen, similar to every other programming language. Within this situation the XML type of HTML is treated as an application where code is examined for processing in opposition to basically a set text document of figures.

The benefit of while using SGML form is the fact that complete mess and lack of knowledge from the technologies is perfectly tolerable. When the browser processes the code then your code is a good example regardless of how invalid. The problem with that's the experience is restricted as to the the browser can aesthetically process towards the consumer, meaning aiding technology is in a severe disadvantage. The benefit of the XML form, especially if it's defined using schema rather than doctype, would be that the document functions as an application where it's naturally self-conscious of its very own structure and what its abilities are. The is definitely valid or it fails, meaning the code is definitely syntactically uniform, making integration of aiding technologies easy and practical. The problem with the XML form is the fact that incompetent and lazy authors cannot publish documents that actually work properly. Personally, I don't observe that like a disadvantage since its a small expectation in absolutely almost every other regard holiday to a type of computing.