What is XHTML?
* XHTML stands for eXtensible Hyper Text Markup Language.
* It is aimed to replace HTML.
* It is almost identical to HTML 4.01
* It is the reformulation of HTML 4.01 as an application of XML.
* It is a stricter, tidier version of HTML.
XHTML 1.0 is the next level of coding as specified by the W3C.
XHTML is a transition / combination of HTML and XML. To change from HTML to XHTML requires just a few changes in your coding styles. The main page to check out is CONVERTING but all the others provide valuable information about this coding technique as well.
XHTML provides the framework for future extensions of HTML and aims to replace HTML in the future. Some resources refer to XHTML as HTML5.
XHTML 1.0 became an official W3C recommendation on January 26, 2000. A W3C recommendation means that the specification is stable, that it has been reviewed by the W3C membership, and that the specification is now a Web standard.
XHTML 1.0 is the first step toward a modular and extensible web environment based on XML (eXtensible Markup Language). It provides the bridge for web designers to use a future based coding and still be able to maintain compatibility with today's browsers.
SGML stands for Standard Generalized Markup Language. Simply put, it is the very root coding of coding. HTML is an application of SGML. XML is a simplified subset of SGML.
DTD stands for Document Type Declaration. It is a set of instructions that states what tags are usable and what (re)action they create. Each browser has a DTD set in it's programming set by the browser companies. This is how some tags will work in only one type of browser or version. It has the tags stated in it's DTD. XML makes it possible to create unique tag sets by applying it's own DTD. This makes the DTD more compatable with more browsers.
2 comments:
If there are any resources that refer to XHTML as HTML5, they are wrong. HTML5 is the next version of HTML being developed by the WHATWG, which includes an XML serialisation known as XHTML5.
A DTD is not a set of instructions. It is a machine readable way of expressing the valid elements, attributes and structure of a document. DTDs do not define what "(re)action they create", whatever that is supposed to mean.
Browsers do not read DTDs for HTML at all, they don't need to. They do not have DTDs built in, they are not the reason that some elements work and others don't.
The reason some elements work in some browsers and not in others is simply because not all browsers have implemented every feature. It has nothing to do with DTDs at all.
For XML, DTDs are never read by browsers. They do not use validating parsers and they don't need to. In fact, many consider DOCTYPES and DTDs completely useless in XML. Thare are better alternatives for validating documents than DTDs.
Actually, I forgot that IE does use a validating parser for XML and so it will read the DTD. But it doesn't support XHTML anyway, and so IE isn't really relevant anyway.
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