Initial Questions

What is HTML

HTML, which stands for Hyper Text Markup Language, is the predominant markup language for web pages. It provides a means to create structured documents by denoting structural semantics for text such as headings, paragraphs, lists etc as well as for links, quotes, and other items. It allows images and objects to be embedded and can be used to create interactive forms. It is written in the form of HTML elements consisting of "tags" surrounded by angle brackets within the web page content.

• HTML stands for Hyper Text Markup Language
• HTML is not a programming language, it is a markup language
• A markup language is a set of markup tags
• HTML uses markup tags to describe web pages

What is XHTML?

Extensible Hypertext Markup Language, or XHTML, is a family of XML markup languages that mirror or extend versions of the widely used Hypertext Markup Language (HTML), the language in which web pages are written.

Versions of XHTML

XHTML 1.0

December 1998 saw the publication of a W3C Working Draft entitled Reformulating HTML in XML. This introduced Voyager, the codename for a new markup language based on HTML 4 but adhering to the stricter syntax rules of XML. By February 1999 the specification had changed name to XHTML 1.0: The Extensible HyperText Markup Language, and in January 2000 it was officially adopted as a W3C Recommendation.

XHTML 1.0 Strict is the XML equivalent to strict HTML 4.01, and includes elements and attributes that have not been marked deprecated in the HTML 4.01 specification.

XHTML 1.0 Transitional is the XML equivalent of HTML 4.01 Transitional, and includes the
presentational elements (such as center, font and strike) excluded from the strict version.

XHTML 1.0 Frameset is the XML equivalent of HTML 4.01 Frameset, and allows for the definition of frameset documents—a common Web feature in the late 1990s.

The second edition of XHTML 1.0 became a W3C Recommendation in August 2002.

What is XML

XML (Extensible Markup Language) is a set of rules for encoding documents electronically. It is defined in the XML 1.0 Specification produced by the W3C and several other related specifications; all are fee-free open standards.

XML’s design goals emphasize simplicity, generality, and usability over the Internet. It is a textual data format, with strong support via Unicode for the languages of the world. Although XML’s design focuses on documents, it is widely used for the representation of arbitrary data structures, for example in web services.

There are a variety of programming interfaces which software developers may use to access XML data, and several schema systems designed to aid in the definition of XML-based languages.

As of 2009, hundreds of XML-based languages have been developed, including RSS, Atom, SOAP, and XHTML. XML-based formats have become the default for most office-productivity tools, including Microsoft Office, OpenOffice.org, and Apple's iWork.