HTML, XHTML, and XML

HTML, XHTML, and XML

1. Definition and Features:

1) html:hyper Text Markup Language Hypertext Markup Language is the first language to write Web pages, but the coding is not standardized, mainly used to control the display and appearance of data. More loosely-structured, less rigorous web language;

① simplicity: Super Text Markup language version upgrades are super-set, which makes them more flexible and easy to use.

② Extensibility: The wide application of Super Text Markup language brings about the enhancement function, the addition of identifiers and so on, the super-text markup language adopts the way of sub-class elements, which guarantees the system extension.

③ platform Independence: Although the personal computer is very popular, but with a lot of other machines such as Mac, the Hypertext Markup language can be used on a wide range of platforms, which is another reason why the World Wide Web (WWW) prevails.

④ Versatility: In addition, HTML is the universal language of the network, a simple, universal, all-in-one markup language. It allows web-makers to create complex pages of text and images that can be browsed by anyone else on the web, regardless of the type of computer or browser used.

2) Xhtml:extensibale Hyper Text Markup Language Extensible Hypertext Markup Language is actually rigorous and accurate HTML, the HTML is standardized, coding more rigorous, is a transition language, HTML to XML transition language;

The evolution of HTML and XHTML:

-HTML 1.0-published (not standard) for the work of the Internet Engineering Working Group (IETF) in June 1993.
-HTML 2.0-released in November 1995 as RFC 1866, declared obsolete after RFC 2854 was released in June 2000
-HTML 3.2--January 14, 1996, the recommended standard
-HTML 4.0--December 18, 1997, the recommended standard
-HTML 4.01 (minor improvements)--December 24, 1999, the recommended standard
-ISO/IEC 15445:2000 ("ISO HTML")-published May 15, 2000, based on strict HTML 4.01 syntax, is the standard of the International Organization for Standardization and the IEC
-XHTML 1.0--, published on January 26, 2000, was the recommended standard for the publication, which was later revised on August 1, 2002.
-XHTML 1.1-released on May 31, 2001

3) Xml:extensibale Markup Language Extensible Markup Language is a cross-platform language that encodes more freely. Provides a way to describe structured data that defines the structure and data type of the data itself and is extensible.

The lack of HTML is realized:
-Does not solve all the problem of interpreting data-such as audio-visual files or chemical formulas, musical symbols and other types of content;
-Performance issues-need to download the entire document, in order to start the search for the file action;
-Scalability, elasticity, legibility are poor;
To solve these problems, experts use SGML to streamline production, and in accordance with the development experience of HTML, produce a set of strict rules, but simple description data language: XML. XML is a more neutral way to let the consumer decide how to digest and present the information provided from the server. The purpose of XML is to provide a mechanism by which information can be accurately described to compensate for the too-expressive nature of HTML.

• The Web page encoding is further developed from the Html=>xhtml=>xml.

2. The difference between the three:

• XHTML compared to HTML:

1) XHTML has good typography and specifications, requires: A. Elements must have an end tag; b. Elements must be nested correctly;

2) XHTML attribute values must be in quotation marks;

3) XHTML does not support attribute minimization (minimized attributes) is: <input disabled> is wrong, must <input disabled= ' disabled ' >

4) The name attribute in XHTML is deprecated and will be removed in later versions

• XML compared to HTML:

1) XML specification is rigorous, such as: Strictly case-sensitive

2) XML tags must be closed, including empty tags

3) XML must have only one root tag

4) XML tags can be customized

• According to this evolutionary process, HTML can be gradually replaced by XML, XML is a more powerful language, more flexible.

---a newcomer, lack of knowledge, shortcomings, welcome to correct me ...

Reference documents:

[1] Standard

[2] CSS authoritative guide (third edition)

[3] http://wenku.baidu.com/Baidu Library

HTML, XHTML, and XML