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Example of HTML |
"In 1980, physicist
Tim Berners-Lee, who was a contractor at
CERN, proposed and prototyped
ENQUIRE, a system for
CERN researchers to use and share documents. In 1989, Berners-Lee wrote a memo proposing an
Internet-based
hypertext system.
Berners-Lee specified HTML and wrote the browser and server software in the last part of 1990. In that year, Berners-Lee and CERN data systems engineer
Robert Cailliau collaborated on a joint request for funding, but the project was not formally adopted by CERN. In his personal notes from 1990 he lists "
some of the many areas in which hypertext is used" and puts an encyclopedia first.
HTML, which stands for
HyperText Markup Language, is the predominant
markup language for
web pages. A markup language is a set of markup tags, and HTML uses markup tags to describe
web pages.
HTML is written in the form of
HTML elements consisting of "tags" surrounded by
angle brackets (like <html>) within the web page content. HTML tags normally come in pairs like <b> and </b>. The first tag in a pair is the
start tag, the second tag is the
end tag (they are also called
opening tags and
closing tags).
The purpose of a
web browser is to read HTML documents and display them as web pages. The browser does not display the HTML tags, but uses the tags to interpret the content of the page.
HTML elements form the building blocks of all websites. HTML allows
images and objects to be embedded and can be used to create
interactive forms. It provides a means to create
structured documents by denoting structural
semantics for text such as headings, paragraphs, lists, links, quotes and other items. It can embed
scripts in languages such as
JavaScript which affect the behavior of HTML webpages.
HTML can also be used to include
Cascading Style Sheets (CSS) to define the appearance and layout of text and other material. The
W3C, maintainer of both HTML and CSS standards, encourages the use of CSS over explicit presentational markup.
One difference in the latest HTML specifications lies in the distinction between the SGML-based specification and the XML-based specification. The XML-based specification is usually called
XHTML to distinguish it clearly from the more traditional definition.
HTML | XHTML |
Allows many shortcuts | Does not allows shortcuts |
Optional opening and closing tag | Requires all elements to have an opening tag and a closing tag |