XHTML or eXtensible HyperText Markup Language is a markup language that has the same expressive capabilities as HTML, but with a stronger syntax.
XHTML can be considered as the cross between HTML and XML in many ways, being a rewriting of HTML in XML. XHTML 1.0 has become a World Wide Web Consortium (W3C) recommendation on January 26, 2000.
Practically XHTML is a modern replacement for the older HTML language, almost identical to the HTML 4.01 standard, an improved, much stricter, cleaner version of HTML 4.0.
If you are familiar with HTML, you will not have any problems in building XHTML pages or converting HTML into XHTML.
To create correct XHTML pages, follow the following guidelines:
1. All labels must be closed and the pair labels are closed by the closing tag.
2. All tags are written in small letters, which means XHTML documents are XML applications. XML is a case sensitive language and distinguishes between lowercase and uppercase.
3. The elements fit in the correct order.
The successive items close in reverse order to how they were opened.
4. The other attribute will be present in all img tags.
5. Structure of an XHTML page. The first 2 lines, DOCTYPE and html, will be additionally specified.
6. DOCTYPE statement. This is an HTML tag, which is why it should not be enclosed with the / XHTML symbol.
7. The HTML tag. In HTML this tag has no attributes. XHTML has the xmlns (XML NameSpace) attribute, with the URL value where the W3C specifications are presented.
The DOCTYPE statement and the HTML tag inform the browser and validators of the document type for a correct interpretation.
XHTML + TIME is an extension of XHTML, providing web support for multimedia timing and synchronization.
Thus, using a few new elements and attributes, XHTML pages can add graphical, audio or video content that can be synchronized with other details along a time frame specified by the author of that page.
Why XHTML + TIME?
HTML is probably the most successful writing language in the world.
Advantages of using XHTML instead of HTML
If the document is pure XHTML 1.0 (without including other markup languages), then you will not notice a big difference, at least not for the time being.
However, as more and more XML tools become available, such as XSLT transformations, you will start to notice the benefits of XHTML.
XForms, as another example, will allow you to edit XHTML documents (or any other XML document) very easily, and in a controllable way.
Web semantic applications will also benefit from the benefits of XHTML documents.
If your document is more than XHTML 1.0, for example, if it includes MathML, SMIL, or SVG, then the benefits are immediate: you can not use them using HTML.
HTML is not written in XML format. You must make the necessary changes to make the document compatible with XML before you can declare it as XML.
HTML Tidy allows you to transform any HTML document into an XHTML document. Amaya is a browser / editor that can save HTML documents as XHTML.
JavaScript or VBScript JavaScript scripts further extend the flexibility and interactivity of web page elements. XHTML + TIME provides a complete object model that extends the current DHTML model, which consists of a set of properties, methods, and events to add interactive features to Web pages.
XHTML + TIME elements behave differently when adding time attributes, depending on the item type.
Thus, we distinguish two types of elements in the XHTML + TIME language:
– content elements: all elements describing the content to be displayed on the page, including the new elements introduced by XHTML + TIME, which refer to multimedia objects (t: animation , t: audio, t: img, t: media and t: video).
The most used XHTML content elements are p, div, span, as well as elements for table descriptions.
By adding XHTML + TIME attributes to a content item, a periodic appearance of the item can be defined.
– Style elements: Describe the style of display for an item.
Among the most used style elements we mention: b, i and em. Attributes applied to a style element cause attachment and removal of display styles over time.