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From Citizendium, the Citizens' Compendium
HyperText Markup Language (HTML) is a set of tags for marking up the content of a web page into distinct sections. Web pages are an network-based implementation of hypertext, or documents that have dynamic links to one another, rather than being in the sequential form of the pages of a book.
HTML resembles old-fashioned typesetting code, or PostScript printer description language, where a block of text is surrounded by tags that indicate how it should appear. HTML allows text to be linked to another file on the Internet, similar to Vannevar Bush's proposed Memory Extender (Memex).
Tim Berners-Lee created the original HTML (and many associated protocols such as HTTP) on a NeXTcube workstation using the NeXTSTEP development environment. He built HTML from prior work on markup languages and hypertext.
Like most markup languages, HTML uses tags to convey information. A typical HTML document has a head section and a body section. The head section contains meta-information like the page's title (which appears in a browser window's name), author, encoding, and any stylesheets that should be applied to the document. The head section also contains any script code that has to be loaded before the body section loads. The body section contains the information that makes up the contents of the document. Tags such as h1 and h2 designate article headings, the a (anchor) tag marks a hyperlink to another document or to another section of the same document, em and strong tags are used for emphasis, etc.
Most HTML tags require both an opening and closing tag. Closing tags are similar to opening tags except for a forward slash before the tag designation. However, there are some HTML tags that do not require a closing tag
HTML can be typed manually in a notepad and saved with a .html extension. It can be opened and viewed using a browser.
Find below a few examples of html tags
|Indicates beginning and end of HTML document|
|Indicates beginning and end of head section of HTML document|
|Indicates beginning and end of page title, which is visible in the client browser|
|Indicates beginning and end of body of HTML document|
|Indicates beginning and end of centered text|
|Indicates beginning and end of heading 1 paragraph format|
|Indicates beginning and end of heading 2 paragraph format|
|Indicates beginning and end of bold text|
|Indicates beginning and end of italicized text|
|Indicates line break. Example of tag that does not have closing tag|
|Used to specify font formatting|
The HTML standard is maintained by the World Wide Web Consortium (commonly shortened to W3C). The current official version of HTML is 4.01 which was ratified in December 1999. 4.01 is a minor step from 1997's 4.0 standard.
HTML is complemented by Extensible HyperText Markup Language (XHTML), which is a reformulation of HTML using Extensible Markup Language (XML). The current version of XHTML is XHTML 1.1, which was released in 2001. XHTML is widely used on sites intended for use on mobile devices, where browsers are less forgiving than on computers. The W3C has also combined XHTML 1.1 with a variety of other formats including Scalable Vector Graphics (SVG) and RDFa, to allow XHTML users to include elements from these vocabularies - representing vector graphical elements, and Semantic Web metadata respectively.
Future of HTML
The W3C recently reformed the HTML Working Group to work on HTML 5 by formalising the work done by the WHAT WG, an unofficial working group setup by representatives from Google, Apple and Opera Software. HTML 5 is planned to be the next version of HTML, and will be serialised in both the SGML-derived syntax and as XHTML.
The W3C also has a Working Group pursuing XHTML 2, but this has had a cold reception from browser vendors and seems unlikely to play an important part in the future of the Web.
An example of a simple HTML Page:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.or/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Example Page</title> </head> <body> <h1>This is a headline</h1> <p>This text is part of a paragraph.</p> </body> </html>
Tutorials and guides
HTML Markup Validators
- W3C's Markup Validator
- WDG HTML Validator
- Validators and checkers (Site Check)
- Off-line HTML Validator v1.0 for Windows
- Web Applications 1.0 A specification generally referred to as "HTML 5". The Web Hypertext Application Technology working group are an independent initiative who cooperate with the W3C.