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HYPERTEXT MARKUP LANGUAGE (HTML) is the standard markup language for creating web pages and web applications . With Cascading Style Sheets (CSS) and JavaScript it forms a triad of cornerstone technologies for the World Wide Web . Web browsers receive HTML
HTML
documents from a webserver or from local storage and render them into multimedia web pages. HTML
HTML
describes the structure of a web page semantically and originally included cues for the appearance of the document.

HTML
HTML
elements are the building blocks of HTML
HTML
pages. With HTML constructs, images and other objects, such as interactive forms, may be embedded into the rendered page. It provides a means to create structured documents by denoting structural semantics for text such as headings, paragraphs, lists, links , quotes and other items. HTML elements are delineated by _tags_, written using angle brackets . Tags such as and introduce content into the page directly. Others such as ... surround and provide information about document text and may include other tags as sub-elements. Browsers do not display the HTML tags, but use them to interpret the content of the page.

HTML
HTML
can embed programs written in a scripting language such as JavaScript which affect the behavior and content of web pages. Inclusion of CSS
CSS
defines the look and layout of content. The World Wide Web Consortium (W3C), maintainer of both the HTML
HTML
and the CSS standards, has encouraged the use of CSS
CSS
over explicit presentational HTML
HTML
since 1997.

CONTENTS

* 1 History

* 1.1 Development

* 1.2 HTML
HTML
versions timeline

* 1.2.1 HTML
HTML
draft version timeline * 1.2.2 XHTML versions

* 2 Markup

* 2.1 Elements

* 2.1.1 Element examples * 2.1.2 Attributes

* 2.2 Character and entity references * 2.3 Data types * 2.4 Document type declaration

* 3 Semantic
Semantic
HTML
HTML

* 4 Delivery

* 4.1 HTTP * 4.2 HTML
HTML
e-mail * 4.3 Naming conventions * 4.4 HTML Application

* 5 HTML4 variations

* 5.1 SGML-based versus XML-based HTML
HTML
* 5.2 Transitional versus strict * 5.3 Frameset versus transitional * 5.4 Summary of specification versions

* 6 HTML5 variations

* 6.1 WHATWG HTML
HTML
versus HTML5

* 7 Hypertext features not in HTML
HTML
* 8 WYSIWYG editors * 9 See also * 10 References * 11 External links

HISTORY

The historic logo made by the W3C An example website written in HTML
HTML
Code

DEVELOPMENT

Tim Berners-Lee

In 1980, physicist Tim Berners-Lee , 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
Internet
-based hypertext system. Berners-Lee specified HTML
HTML
and wrote the browser and server software in late 1990. 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 listed "some of the many areas in which hypertext is used" and put an encyclopedia first.

The first publicly available description of HTML
HTML
was a document called " HTML
HTML
Tags", first mentioned on the Internet
Internet
by Tim Berners-Lee in late 1991. It describes 18 elements comprising the initial, relatively simple design of HTML. Except for the hyperlink tag, these were strongly influenced by SGMLguid , an in-house Standard Generalized Markup Language (SGML)-based documentation format at CERN. Eleven of these elements still exist in HTML
HTML
4.

HTML
HTML
is a markup language that web browsers use to interpret and compose text, images, and other material into visual or audible web pages. Default characteristics for every item of HTML
HTML
markup are defined in the browser, and these characteristics can be altered or enhanced by the web page designer's additional use of CSS
CSS
. Many of the text elements are found in the 1988 ISO technical report TR 9537 _Techniques for using SGML_, which in turn covers the features of early text formatting languages such as that used by the RUNOFF command developed in the early 1960s for the CTSS (Compatible Time-Sharing System) operating system: these formatting commands were derived from the commands used by typesetters to manually format documents. However, the SGML concept of generalized markup is based on elements (nested annotated ranges with attributes) rather than merely print effects, with also the separation of structure and markup; HTML has been progressively moved in this direction with CSS.

Berners-Lee considered HTML
HTML
to be an application of SGML. It was formally defined as such by the Internet
Internet
Engineering Task Force (IETF) with the mid-1993 publication of the first proposal for an HTML specification, the " Hypertext Markup Language (HTML)" Internet
Internet
Draft by Berners-Lee and Dan Connolly , which included an SGML Document Type Definition to define the grammar. The draft expired after six months, but was notable for its acknowledgment of the NCSA Mosaic browser's custom tag for embedding in-line images, reflecting the IETF's philosophy of basing standards on successful prototypes. Similarly, Dave Raggett 's competing Internet-Draft, "HTML+ (Hypertext Markup Format)", from late 1993, suggested standardizing already-implemented features like tables and fill-out forms.

After the HTML
HTML
and HTML+ drafts expired in early 1994, the IETF created an HTML
HTML
Working Group, which in 1995 completed " HTML
HTML
2.0", the first HTML
HTML
specification intended to be treated as a standard against which future implementations should be based.

Further development under the auspices of the IETF was stalled by competing interests. Since 1996, the HTML
HTML
specifications have been maintained, with input from commercial software vendors, by the World Wide Web Consortium (W3C). However, in 2000, HTML
HTML
also became an international standard (ISO /IEC 15445:2000). HTML
HTML
4.01 was published in late 1999, with further errata published through 2001. In 2004, development began on HTML5 in the Web Hypertext Application Technology Working Group (WHATWG), which became a joint deliverable with the W3C in 2008, and completed and standardized on 28 October 2014.

HTML
HTML
VERSIONS TIMELINE

November 24, 1995 HTML
HTML
2.0 was published as IETF RFC 1866 . Supplemental RFCs added capabilities:

* November 25, 1995: RFC 1867 (form-based file upload) * May 1996: RFC 1942 (tables) * August 1996: RFC 1980 (client-side image maps) * January 1997: RFC 2070 (internationalization )

January 14, 1997 HTML
HTML
3.2 was published as a W3C Recommendation . It was the first version developed and standardized exclusively by the W3C, as the IETF had closed its HTML Working Group on September 12, 1996. Initially code-named "Wilbur", HTML
HTML
3.2 dropped math formulas entirely, reconciled overlap among various proprietary extensions and adopted most of Netscape
Netscape
's visual markup tags. Netscape's blink element and Microsoft
Microsoft
's marquee element were omitted due to a mutual agreement between the two companies. A markup for mathematical formulas similar to that in HTML
HTML
was not standardized until 14 months later in MathML . December 18, 1997 HTML
HTML
4.0 was published as a W3C Recommendation. It offers three variations:

* Strict, in which deprecated elements are forbidden * Transitional, in which deprecated elements are allowed * Frameset, in which mostly only frame related elements are allowed.

Initially code-named "Cougar", HTML
HTML
4.0 adopted many browser-specific element types and attributes, but at the same time sought to phase out Netscape's visual markup features by marking them as deprecated in favor of style sheets. HTML
HTML
4 is an SGML application conforming to ISO 8879 – SGML. April 24, 1998 HTML
HTML
4.0 was reissued with minor edits without incrementing the version number. December 24, 1999 HTML
HTML
4.01 was published as a W3C Recommendation. It offers the same three variations as HTML
HTML
4.0 and its last errata were published on May 12, 2001. May 2000 ISO/IEC 15445:2000 ("ISO HTML", based on HTML
HTML
4.01 Strict) was published as an ISO/IEC international standard. In the ISO this standard falls in the domain of the ISO/IEC JTC1/SC34 (ISO/IEC Joint Technical Committee 1, Subcommittee 34 – Document description and processing languages). After HTML
HTML
4.01, there was no new version of HTML
HTML
for many years as development of the parallel, XML-based language XHTML occupied the W3C's HTML
HTML
Working Group through the early and mid-2000s. October 28, 2014 HTML5 was published as a W3C Recommendation. November 1, 2016 HTML
HTML
5.1 was published as a W3C Recommendation.

HTML
HTML
Draft Version Timeline

_ Logo of HTML5 October 1991 HTML
HTML
Tags_, an informal CERN document listing 18 HTML
HTML
tags, was first mentioned in public. June 1992 First informal draft of the HTML
HTML
DTD, with seven subsequent revisions (July 15, August 6, August 18, November 17, November 19, November 20, November 22) November 1992 HTML
HTML
DTD 1.1 (the first with a version number, based on RCS revisions, which start with 1.1 rather than 1.0), an informal draft June 1993 Hypertext Markup Language was published by the IETF IIIR Working Group as an Internet
Internet
Draft (a rough proposal for a standard). It was replaced by a second version one month later, followed by six further drafts published by IETF itself that finally led to HTML
HTML
2.0 in RFC 1866 . November 1993 HTML+ was published by the IETF as an Internet
Internet
Draft and was a competing proposal to the Hypertext Markup Language draft. It expired in May 1994. April 1995 (authored March 1995) HTML
HTML
3.0 was proposed as a standard to the IETF, but the proposal expired five months later (28 September 1995) without further action. It included many of the capabilities that were in Raggett's HTML+ proposal, such as support for tables, text flow around figures and the display of complex mathematical formulas. W3C began development of its own Arena browser as a test bed for HTML
HTML
3 and Cascading Style Sheets, but HTML
HTML
3.0 did not succeed for several reasons. The draft was considered very large at 150 pages and the pace of browser development, as well as the number of interested parties, had outstripped the resources of the IETF. Browser vendors, including Microsoft
Microsoft
and Netscape
Netscape
at the time, chose to implement different subsets of HTML
HTML
3's draft features as well as to introduce their own extensions to it. (see Browser wars ). These included extensions to control stylistic aspects of documents, contrary to the "belief that such things as text color, background texture, font size and font face were definitely outside the scope of a language when their only intent was to specify how a document would be organized." Dave Raggett, who has been a W3C Fellow for many years, has commented for example: "To a certain extent, Microsoft built its business on the Web by extending HTML
HTML
features." January 2008 HTML5 was published as a Working Draft by the W3C. Although its syntax closely resembles that of SGML , HTML5 has abandoned any attempt to be an SGML application and has explicitly defined its own "html" serialization, in addition to an alternative XML-based XHTML5 serialization. 2011 HTML5 – Last Call On 14 February 2011, the W3C extended the charter of its HTML Working Group with clear milestones for HTML5. In May 2011, the working group advanced HTML5 to "Last Call", an invitation to communities inside and outside W3C to confirm the technical soundness of the specification. The W3C developed a comprehensive test suite to achieve broad interoperability for the full specification by 2014, which was the target date for recommendation. In January 2011, the WHATWG renamed its "HTML5" living standard to "HTML". The W3C nevertheless continues its project to release HTML5. 2012 HTML5 – Candidate Recommendation In July 2012, WHATWG and W3C decided on a degree of separation. W3C will continue the HTML5 specification work, focusing on a single definitive standard, which is considered as a "snapshot" by WHATWG. The WHATWG organization will continue its work with HTML5 as a "Living Standard". The concept of a living standard is that it is never complete and is always being updated and improved. New features can be added but functionality will not be removed. In December 2012, W3C designated HTML5 as a Candidate Recommendation. The criterion for advancement to W3C Recommendation is "two 100% complete and fully interoperable implementations". 2014 HTML5 – Proposed Recommendation and Recommendation In September 2014, W3C moved HTML5 to Proposed Recommendation. On 28 October 2014, HTML5 was released as a stable W3C Recommendation, meaning the specification process is complete.

XHTML Versions

Main article: XHTML

XHTML is a separate language that began as a reformulation of HTML 4.01 using XML
XML
1.0. It is no longer being developed as a separate standard.

* XHTML 1.0 was published as a W3C Recommendation on January 26, 2000 and was later revised and republished on August 1, 2002. It offers the same three variations as HTML
HTML
4.0 and 4.01, reformulated in XML, with minor restrictions. * XHTML 1.1 was published as a W3C Recommendation on May 31, 2001. It is based on XHTML 1.0 Strict, but includes minor changes, can be customized, and is reformulated using modules in the W3C recommendation "Modularization of XHTML", which was published on April 10, 2001. * XHTML 2.0 was a working draft, work on it was abandoned in 2009 in favor of work on HTML5 and X HTML5 . XHTML 2.0 was incompatible with XHTML 1.x and, therefore, would be more accurately characterized as an XHTML-inspired new language than an update to XHTML 1.x. * An XHTML syntax, known as "XHTML5.1", is being defined alongside HTML5 in the HTML5 draft.

MARKUP

HTML
HTML
markup consists of several key components, including those called _tags_ (and their _attributes_), character-based _data types_, _character references_ and _entity references_. HTML
HTML
tags most commonly come in pairs like and , although some represent _empty elements_ and so are unpaired, for example . The first tag in such a pair is the _start tag_, and the second is the _end tag_ (they are also called _opening tags_ and _closing tags_).

Another important component is the HTML
HTML
_document type declaration _, which triggers standards mode rendering.

The following is an example of the classic Hello world program , a common test employed for comparing programming languages , scripting languages and markup languages . This example is made using 9 lines of code :

This is a title Hello world!

_(The text between and describes the web page, and the text between and is the visible page content. The markup text "This is a title" defines the browser page title.)_

The Document Type Declaration is for HTML5. If a declaration is not included, various browsers will revert to "quirks mode " for rendering.

ELEMENTS

Main article: HTML element

HTML
HTML
documents imply a structure of nested HTML
HTML
elements . These are indicated in the document by HTML
HTML
_tags_, enclosed in angle brackets thus:

In the simple, general case, the extent of an element is indicated by a pair of tags: a "start tag" and "end tag" . The text content of the element, if any, is placed between these tags.

Tags may also enclose further tag markup between the start and end, including a mixture of tags and text. This indicates further (nested) elements, as children of the parent element.

The start tag may also include _attributes_ within the tag. These indicate other information, such as identifiers for sections within the document, identifiers used to bind style information to the presentation of the document, and for some tags such as the used to embed images, the reference to the image resource.

Some elements, such as the line break , do not permit _any_ embedded content, either text or further tags. These require only a single empty tag (akin to a start tag) and do not use an end tag.

Many tags, particularly the closing end tag for the very commonly used paragraph element , are optional. An HTML
HTML
browser or other agent can infer the closure for the end of an element from the context and the structural rules defined by the HTML
HTML
standard. These rules are complex and not widely understood by most HTML
HTML
coders.

The general form of an HTML element is therefore: ''content''. Some HTML
HTML
elements are defined as _empty elements_ and take the form . Empty elements may enclose no content, for instance, the tag or the inline tag. The name of an HTML element is the name used in the tags. Note that the end tag's name is preceded by a slash character, "/", and that in empty elements the end tag is neither required nor allowed. If attributes are not mentioned, default values are used in each case.

Element Examples

Header of the HTML
HTML
document: .... The title is included in the head, for example:

The Title

Headings: HTML
HTML
headings are defined with the to tags:

Heading level 1 Heading level 2 Heading level 3 Heading level 4 Heading level 5 Heading level 6

Paragraphs:

Paragraph
Paragraph
1 Paragraph
Paragraph
2

Line breaks:. The difference between and is that "br" breaks a line without altering the semantic structure of the page, whereas "p" sections the page into paragraphs . Note also that "br" is an _empty element_ in that, although it may have attributes, it can take no content and it may not have an end tag.

This is a paragraph with line breaks

This is a link in HTML. To create a link the tag is used. The href= attribute holds the URL address of the link.

A link to!

Inputs:

There are many possible ways a user can give input/s like:

1 2 3

Comments:

Comments can help in the understanding of the markup and do not display in the webpage.

There are several types of markup elements used in HTML: Structural markup indicates the purpose of text For example, Golf establishes "Golf" as a second-level heading . Structural markup does not denote any specific rendering, but most web browsers have default styles for element formatting. Content may be further styled using Cascading Style Sheets (CSS). Presentational markup indicates the appearance of the text, regardless of its purpose For example, boldface indicates that visual output devices should render "boldface" in bold text, but gives little indication what devices that are unable to do this (such as aural devices that read the text aloud) should do. In the case of both bold and italic, there are other elements that may have equivalent visual renderings but that are more semantic in nature, such as strong text and emphasised text respectively. It is easier to see how an aural user agent should interpret the latter two elements. However, they are not equivalent to their presentational counterparts: it would be undesirable for a screen-reader to emphasize the name of a book, for instance, but on a screen such a name would be italicized. Most presentational markup elements have become deprecated under the HTML
HTML
4.0 specification in favor of using CSS
CSS
for styling. Hypertext markup makes parts of a document into links to other documents An anchor element creates a hyperlink in the document and its href attribute sets the link's target URL . For example, the HTML
HTML
markup, Wikipedia, will render the word as a hyperlink. To render an image as a hyperlink, an "img" element is inserted as content into the "a" element. Like "br", "img" is an empty element with attributes but no content or closing tag. .

Attributes

Main article: HTML attribute

Most of the attributes of an element are name-value pairs , separated by "=" and written within the start tag of an element after the element's name. The value may be enclosed in single or double quotes, although values consisting of certain characters can be left unquoted in HTML
HTML
(but not XHTML) . Leaving attribute values unquoted is considered unsafe. In contrast with name-value pair attributes, there are some attributes that affect the element simply by their presence in the start tag of the element, like the ismap attribute for the img element.

There are several common attributes that may appear in many elements :

* The id attribute provides a document-wide unique identifier for an element. This is used to identify the element so that stylesheets can alter its presentational properties, and scripts may alter, animate or delete its contents or presentation. Appended to the URL of the page, it provides a globally unique identifier for the element, typically a sub-section of the page. For example, the ID "Attributes" in http://en.wikipedia.org/wiki/HTML#Attributes * The class attribute provides a way of classifying similar elements. This can be used for semantic or presentation purposes. For example, an HTML
HTML
document might semantically use the designation class="notation" to indicate that all elements with this class value are subordinate to the main text of the document. In presentation, such elements might be gathered together and presented as footnotes on a page instead of appearing in the place where they occur in the HTML source. Class attributes are used semantically in microformats . Multiple class values may be specified; for example class="notation important" puts the element into both the "notation" and the "important" classes. * An author may use the style attribute to assign presentational properties to a particular element. It is considered better practice to use an element's id or class attributes to select the element from within a stylesheet , though sometimes this can be too cumbersome for a simple, specific, or ad hoc styling. * The title attribute is used to attach subtextual explanation to an element. In most browsers this attribute is displayed as a tooltip .

* The lang attribute identifies the natural language of the element's contents, which may be different from that of the rest of the document. For example, in an English-language document:

Oh well, c'est la vie, as they say in France.

The abbreviation element, abbr, can be used to demonstrate some of these attributes :

HTML
HTML

This example displays as HTML; in most browsers, pointing the cursor at the abbreviation should display the title text " Hypertext Markup Language."

Most elements take the language-related attribute dir to specify text direction, such as with "rtl" for right-to-left text in, for example, Arabic , Persian or Hebrew .

CHARACTER AND ENTITY REFERENCES

See also: List of XML
XML
and HTML
HTML
character entity references and Unicode and HTML

As of version 4.0, HTML
HTML
defines a set of 252 character entity references and a set of 1,114,050 numeric character references , both of which allow individual characters to be written via simple markup, rather than literally. A literal character and its markup counterpart are considered equivalent and are rendered identically.

The ability to "escape" characters in this way allows for the characters

* _ MSN TV _

* Software no longer in development shown in _italics_

* Category
Category
* Commons * Internet
Internet
portal * Software portal

* v * t * e

List of International Electrotechnical Commission standards

IEC STANDARDS

* IEC 60027 * IEC 60034 * IEC 60038 * IEC 60062 * IEC 60063 * IEC 60068 * IEC 60112 * IEC 60228 * IEC 60269 * IEC 60297 * IEC 60309
IEC 60309
* IEC 60320 * IEC 60364 * IEC 60446 * IEC 60559 * IEC 60601

* IEC 60870

* IEC 60870-5 * IEC 60870-6

* IEC 60906-1 * IEC 60908 * IEC 60929

* IEC 60958

* AES3 * S/PDIF

* IEC 61030

* IEC 61131

* IEC 61131-3

* IEC 61158 * IEC 61162 * IEC 61334 * IEC 61346 * IEC 61355 * IEC 61400 * IEC 61499 * IEC 61508 * IEC 61511 * IEC 61850 * IEC 61883 * IEC 61960 * IEC 61968 * IEC 61970 * IEC 62014-4 * IEC 62056 * IEC 62061 * IEC 62196 * IEC 62262 * IEC 62264 * IEC 62304 * IEC 62325 * IEC 62351 * IEC 62365 * IEC 62366 * IEC 62379 * IEC 62386 * IEC 62455 * IEC 62680 * IEC 62682 * IEC 62700

ISO/IEC STANDARDS

* ISO/IEC 646 * ISO/IEC 2022 * ISO/IEC 5218 * ISO/IEC 6429 * ISO/IEC 6523 * ISO/IEC 7810 * ISO/IEC 7811 * ISO/IEC 7812 * ISO/IEC 7813 * ISO/IEC 7816 * ISO/IEC 7942 * ISO/IEC 8613 * ISO/IEC 8632 * ISO/IEC 8652 * ISO/IEC 8859 * ISO/IEC 9126 * ISO/IEC 9293 * ISO/IEC 9592 * ISO/IEC 9593 * ISO/IEC 9899 * ISO/IEC 9945 * ISO/IEC 9995 * ISO/IEC 10021 * ISO/IEC 10116 * ISO/IEC 10165 * ISO/IEC 10179 * ISO/IEC 10646 * ISO/IEC 10967 * ISO/IEC 11172 * ISO/IEC 11179 * ISO/IEC 11404 * ISO/IEC 11544 * ISO/IEC 11801 * ISO/IEC 12207 * ISO/IEC 13250 * ISO/IEC 13346 * ISO/IEC 13522-5 * ISO/IEC 13568 * ISO/IEC 13818 * ISO/IEC 14443 * ISO/IEC 14496 * ISO/IEC 14882 * ISO/IEC 15288 * ISO/IEC 15291 * ISO/IEC 15408 * ISO/IEC 15444 * ISO/IEC 15445 * ISO/IEC 15504 * ISO/IEC 15511 * ISO/IEC 15693 * ISO/IEC 16262 * ISO/IEC 17024 * ISO/IEC 17025 * ISO/IEC 18000 * ISO/IEC 18004 * ISO/IEC 18014 * ISO/IEC 19752 * ISO/IEC 19757 * ISO/IEC 19770 * ISO/IEC 19788 * ISO/IEC 20000 * ISO/IEC 21000 * ISO/IEC 21827 * ISO/IEC 23003 * ISO/IEC 23270 * ISO/IEC 23360 * ISO/IEC 24707 * ISO/IEC 24727 * ISO/IEC 24744 * ISO/IEC 26300 * ISO/IEC 27000 * ISO/IEC 27000-series * ISO/IEC 27002 * ISO/IEC 27040 * ISO/IEC 29119 * ISO/IEC 33001 * ISO/IEC 42010 * ISO/IEC 80000 * ISO/IEC 38500 * ISO/IEC 4909

RELATED

* International Electrotechnical Commission

AUTHORITY CONTROL

* LCCN : sh95002791 * GND : 4373477-7 * BNF : cb12493600c (data) * BNE : XX539726

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HTML
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