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XHTML stands for extensible HyperText Markup Language and is a cross between HTML and XML. XHTML was developed by the W3C to help web developers make the transition from HTML to XML.
- To create a stricter standard for making web pages, reducing incompatibilities between browsers.
- To create a standard that can be used on a variety of different devices without changes.
There are several main changes in XHTML from HTML
- All tags must be in lower case
- All documents must have a doctype
- All documents must be properly formed
- All tags must be closed
- All attributes must be added properly
- The name attribute has changed
- Attributes cannot be shortened
- All tags must be properly nested
HTML was originally Developed by Tim Berners-Lee, now director of the World Wide Web Consortium, keepers and communicators of most internet standards. XHTML1 is a reformulation of HTML4, which was SGML-based, as XML. The changes are of a mere syntactic nature and not visible to the end-user.
XHTML1 comes in three different flavors:
| XHTML | HTML |
| XHTML is case-sensitive | HTML is not case-sensitive |
| XHTML, being XML, must be well-formed. Every element must have an end tag, or use the self-closing tag syntax | HTML allows some end tags and even some start tags to be omitted. |
| All attributes must have a value in XHTML | HTML allows some attributes (e.g., selected) to be minimised. |
| All attribute values must be surrounded by double or single quotes | HTML allows quotes to be omitted if the value contains only alphanumeric characters (and some others). |
| XHTML allows the use of CDATA sections | HTML does not |
| In XHTML, non-empty elements require both a start and an end tag | In HTML, certain elements allow the omission of either or both |
| XHTML allows the use of processing instructions | HTML does not |
| In XHTML, tag names and attribute names are case sensitive | In HTML, they are case insensitive. |
| XHTML uses XML parsing requirements | HTML uses its own which are defined much more closely to the way browsers actually handle HTML today. |
We use XHTML because of some important reasons those are given below
- It is the first step toward a modular and extensible web based on XML.
- It provides the bridge for web designers to enter the web of the future, while still being able to maintain compatibility with today's HTML 4 browsers.
- Develop sophisticated behaviours that work across multiple browsers and platforms.
- Comply with accessibility laws and guidelines without sacrificing beauty, performance, or sophistication.
- Redesign in hours instead of days or weeks, reducing costs.
- It can be used by mobile devices.
- It is possible to use XML tools with it.