Info on XHTML

XHTML (Extensible Hyper Text Markup Language): Its extended, cleaner and sticker version of HTML, almost identical to HTML4.0. It is based on XML application, so one can say its a combination of HTML and XML.

Basic difference between HTML and XHTML are:

• XHTML elements must be properly nested.
• XHTML elements must always be closed.
• XHTML elements must be in lower case.
• XHTML documents must have one root element.

XHTML syntax rules are:

• Attribute names must be in lower case.
• Attribute values must be quoted.
• Attribute minimization is forbidden.
• The id attribute replaces the name attribute.
• The XHTML DTD defines mandatory elements :Doctype declaration, html,head and body tags are mandatory in XHTML documents.

Doctype specifies which DTD(Document type definition) is used by XHTML document. A DTD specifies the syntax of a web page in SGML. An XHTML DTD describes in precise, computer-readable language, the allowed syntax of XHTML markup.
There are 3 types of XHTML DTD

1. XHTML 1.1 Strict :for clean markup and free of presentational clutter. It declared as: !DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"
2. XHTML 1.1 Transitional : It is used when user want to use HTML presentational features. It declared as: !DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"
3. XHTML 1.1 Frameset : When HTML frames are used. It declared as: !DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd"

After creating xhtml file and adding correct DTD, it can be validated using W3C Validator, using link http://www.w3schools.com/xhtml/default.asp

Web 1.0, Web 2.0, Web 3.0

Web1.0: The information published on the web in a static manner. It is like your word document on the web with pictures and formatting done neatly. Hyper-linking the web-pages and bookmarking were two of the most important aspect of Web1.0 world. Even today more than 70% users are only familiar with Web1.0.
Web2.0: This term was coined by Tim O’Reilly The information published in web2.0 world is very different from web1.0. There is a very high importance given on usability and sharing. The information published in Web2.0 world travels like wild fire, either partially or in full. Web2.0 world has less clutter coupled with easy retrieval of precise information and furthermore building upon that information and sharing it further. Widgets and Tagging are two important features of Web2.0. For a comprehensive information on web2.0
Web3.0: To be honest, there are varied perceptions of what Web3.0 is. It is purely a word coined as the next version of Web2.0. One basic thing that everyone accept is Web3.0 will be a maze / network of application working together homogeneously. The users can do anything and everything they want from a single source on the web. There is yet a lot of time for Web3.0 world to arrive.

Web 1.0 --> Web 2.0
DoubleClick --> Google AdSense
Ofoto --> Flickr
Akamai --> BitTorrent
mp3.com --> Napster
Britannica Online --> Wikipedia
personal websites --> blogging
evite --> upcoming.org and EVDB
domain name speculation --> search engine optimization
page views --> cost per click
screen scraping --> web services
publishing --> participation
content management systems --> wikis
directories (taxonomy) --> tagging ("folksonomy")
stickiness --> syndication