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9-Apr-12

XHTML

http://www.w3schools.com/xhtml/

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What is XHTML?

XHTML stands for Extensible Hypertext Markup

Language

XHTML is aimed to replace HTML

XHTML is almost identical to HTML 4.01 XHTML is a stricter and cleaner version of HTML

XML (Extensible Markup Language) is a markup

language designed for describing data

XHTML is HTML redefined as an XML application

XHTML is a bridge between HTML and XML

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The problem with HTML

HTML started out as a way of way of describing thestructure of documents, with tags to indicate headers,

paragraphs, and the like

Because people wanted to control the appearance of

documents, HTML acquired tags to control fonts,

alignment, etc.

The result is a markup language that does both, but isnt

very good at either

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HTML vs. XML

XML looks a lot like HTML, but--

HTML uses a fixed set of

tags

With XML you make up your

own tags (and define what they

mean in a separate document)

HTML is designed to

display data to humans

XML is designed to describe

data to computers

Browsers are very tolerant

of errors in HTML

XML documents must be well-

formed (syntactically correct)

All browsers can display

HTML

All modern browsers display

XML, but in various ways

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From HTML to XHTML, I

XHTML elements must be properly nested

bold and italic is wrong

XHTML documents must be well-formed

... ...

Tag names must be in lowercase

All XHTML elements must be closed

If an HTML tag is not a container, close it like this:
, ,

Note: Some older browsers require a space before the /

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From HTML to XHTML, II

Attribute names must also be in lower case

Example:

Attribute values must be quoted

Example:

Attribute minimization is forbidden

Example:,

cannot be abbreviated to

The id attribute replaces the name attribute

Wrong: Right:

Best:

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SGML and DTDs

SGMLstands for Standard Generalized Markup Language

HTML, XHTML, XML and many other markup languages are

defined in SGML

A DTD, or Document Type Definition describes the syntax touse for the current document

There are three different DTDs for XHTML--you can pick the

one you want

These DTDs are public and on the web You must start your XHTML document with a reference to one of these

DTDs

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DOCTYPE declaration, I

Every XHTML document must begin with one of the DOCTYPEdeclarations (DTDs):

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DOCTYPE declaration, II

The main DTDs are as follows:

1.0 Strict

Use for really clean markup, with no display information (no

font, color, or size information)

Use with CSS (Cascading Style Sheets) if you want to define

how the document should look

1.0 Transitional

Use with standard HTML and/or with CSS

Allows deprecated HTML elements

1.0 Frameset

Use if your document uses HTML frames

1.1

Like 1.0 Strict, but with added support for Chinese

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An XHTML Example

A simple document

A simple paragraph.

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Extension

A file containing an HTML page should have theextension .html

According to W3C, an XHTML page should have the

extension .xhtml

However...

I have had trouble getting JavaScript to work on pages with

this extension

I recommend sticking with .html, at least for now

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Tools

Dave Raggett's HTML TIDY,http://tidy.sourceforge.net/,

is a free UNIX tool for checking and cleaning up

HTML pages

The W3C HTML Validation Tool

http://validator.w3.org/ is an HTML form for

checking (but not fixing) HTML and XHTML

documents

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Vocabulary

SGML: Standard Generalized Markup Language HTML: Hypertext Markup Language

XHTML: eXtensible Hypertext Markup Language

XML: eXtensible Markup Language

DTD: Document Type Definition

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The End