A markup language used to structure text and multimedia documents and to set up hypertext links between documents, used extensively on the World Wide Web.
[H(yper)t(ext) M(arkup) L(anguage).]
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A markup language used to structure text and multimedia documents and to set up hypertext links between documents, used extensively on the World Wide Web.
[H(yper)t(ext) M(arkup) L(anguage).]
(HyperText Markup Language) The document format used on the Web. Web pages are built with HTML tags (codes) embedded in the text. HTML defines the page layout, fonts and graphic elements as well as the hypertext links to other documents on the Web. Each link contains the URL, or address, of a Web page residing on the same server or any server worldwide, hence "World Wide" Web.
HTML 2.0 was defined by the Internet Engineering Task Force (IETF) with a basic set of features, including interactive forms capability. Subsequent versions added more features such as blinking text, custom backgrounds and tables of contents. However, each new version requires agreement on the tags used, and browsers must be modified to implement those tags. See HTML tag.
HTML Itself Is Not a Programming Language
HTML is a markup language (the ML in HTML) that uses a fixed set of markup tags. A markup language can also be thought of as a "presentation language," but it is not a programming language. You cannot "if this-do that" like you can in Java, JavaScript or C++. However, in order to make pages interactive, programming code can be embedded in an HTML page. For example, JavaScript is widely interspersed in Web pages (HTML pages) for that purpose. See JavaScript and VBScript.
HTML was conceived as a simple markup language to render research documents. No one originally envisioned Web pages turning into multimedia extravaganzas. HTML pages have been reworked, jury-rigged and extended into full-blown applications. As a result, the source code behind today's Web pages is often a hideous concoction of tags and scripting. See HTML tag, XML, XHTML and SGML.
| Accessing a Web document requires typing in the address, or URL (Uniform Resource Locator), of the home page in your Web browser. The home page is an HTML document, which contains hypertext links to other HTML documents that can be stored on the same server or on a server anywhere in the world. |
| Web browsers communicate with Web servers via the TCP/IP protocol. The browser sends HTTP requests to the server, which responds with HTML pages and possibly additional programs in the form of ActiveX controls or Java applets. |
The authoring language used in the creation of documents for the World Wide Web.
Investopedia Says:
If you want to see what HTML language looks like, then, in your browser, click on "view" then "view source." Those hundreds of tags and coding is what makes up HTML.
Uniform coding for defining Web documents. The browser used by the user examines the HTML to ascertain the manner in which to display the graphics, text, and other multimedia components. The use of HTML is recommended in developing intranets/extranets because it is easier to program than window environments such as Motif or Microsoft Windows. HTML is a good integrating tool for data base applications and information systems. It facilitates the use of hyperlinks and search engines, enabling the easy sharing of identical information among different responsibility segments of the company. Intranet data usually goes from back-end sources (e.g., mainframe host) to the Web server to users (e.g., customers) in HTML format.
Hypertext Markup Language (HTML) is an authoring tool that is used in creating Internet Web pages. It is the preferred tool for those who wish to make their Web page more accessible and userfriendly because it is able to accelerate downloading over the Internet, although its quickness comes at the expense of formatting control. Users appreciate the way HTML allows Web pages to link both to and from each other. Several Web browsers use HTML to format and structure pages because it is able to reach an extremely large audience. Many Web designers who use HTML find it simple to learn and easy to use, because it offers a stripped down approach to Web design that does not rely a lot on extraneous features. Another aspect of its popularity is its ability to deal primarily with bandwidth-friendly text documents.
Internet lingo is full of acronyms and buzzwords. When you consider what each letter in HTML stands for, it may be easier to understand exactly what it does and how it works. As Joe Burns stated on www.htmlgoodies.com: "Hyper is the opposite of linear. It used to be that computer programs had to move in a linear fashion. This before this, this before this, and so on. HTML does not hold to that pattern and allows the person viewing the World Wide Web page to go anywhere, any time they want. Text is what you will use. Real, honest to goodness English letters. Mark up is what you will do. You will write in plain English and then mark up what you wrote. Language because they needed something that started with 'L' to finish HTML and Hypertext Markup Louie didn't flow correctly. Because it's a language, really—but the language is plain English."
The History of Html
HTML, along with Hypertext Transport Protocol (HTTP) and uniform resource locator (URL), were created by Tim Berners-Lee in the latter part of the 1980s. Berners-Lee was collaborating in Switzerland at the CERN physics laboratory with another scientist by the name of Robert Calliau. When Berners-Lee was faced with the problem of organizing his notes, he created HTML to make the information accessible and easy to link.
At first, Berners-Lee was faced with the problem of only being able to use his creations on his own personal computer. In an article on Berners-Lee for Time magazine, Joshua Quittner asked the question: "But what if he wanted to add stuff that resided on someone else's computer? First he would need that person's permission, and then he would have to do the dreary work of adding the new material to a central database. An even better solution would be to open up his document—and his computer—to everyone and allow them to link their stuff to his. He could limit access to his colleagues at CERN, but why stop there? Open it up to scientists everywhere! Let it span the networks! In Berners-Lee's scheme there would be no central manager, no central database and no scaling problems. The thing could grow like the Internet itself, open-ended and infinite. …Sohe cobbledtogether a relatively easy-to-learn coding system—HTML—that has come to be the lingua franca of the Web. It's the way Web-content creators put those little colored, underlined links in text, add images, and so on."
Because of his accomplishments, Berners-Lee is considered the father of the World Wide Web and he has received many awards and accolades for his contributions to the world of computers and technology. Awards and accolades may be the only thing he received for his creations. As Quittner put it: "You'd think he would have at least got rich; he had plenty of opportunities. But at every juncture, Berners-Lee chose the non-profit road, both for himself and for his creation."
How Html Works
HTML helps to define the structure of a Web page. It is useful to help set up paragraphs, headers, and default fonts so that a user can always read the text regardless of whether or not they have the font installed on their own personal computer. The acceptance of HTML by Web page designers has allowed them to think of a document as a way of accessing information, rather than a collection of static pages that can only be read when downloaded.
When someone types in a URL or clicks on a Web page link, the browser requests a document from a Web server via the Hypertext Transport Protocol, or HTTP. The server then sends the document back to the user, which is displayed on the browser. The things that are contained in the document (text, photos, audio and video files, etc.) were all put there using HTML structure.
The Drawbacks of Html
HTML is not a perfect tool for designing graphic-intensive sites or those that contain a large overall amount of information. The fact that the documents contained in a HTML structure are static pages does not make it the tool of choice for sites that contain animation, either. It is getting better in that department thanks to the development of different HTML extensions and other upgrades.
HTML also lacks the ability to create custom window sizes, compress files, and other standard navigational controls. Distribution size is also a crucial issue because the standard HTML file format is not suited for delivering a large amount of content over a network. In addition, an HTML programmer may have difficulty dealing with a large number of HTML and graphics files at once. Certain software does exist to help deal with all of these problems.
Dynamic Html and Other Competing Tools
Because of HTML's weaknesses in the area of graphics, dynamic HTML was created to enhance the capabilities in Web page design. As William R. Stanek stated in PC Magazine: "With dynamic HTML, you can create Web pages with eye-popping special effects, animation, and much more without relying on server-side scripts, database engines and hundreds of lines of complicated markup code. One of the key design goals in creating dynamic HTML was easing the complexities involved in interactive multi-media presentations on the Web. An important part of that goal was building the necessary support framework into the browser. The result is that you don't have to rely on controls, plug-ins, or other helper applications to achieve special effects, animation, or anything else that dynamic HTML enables."
Dynamic HTML allows Web page designers to create impressive graphics and animation with minimal coding. These features are visible to viewers almost instantaneously. As Stanek explained, "The key to dynamic HTML in both Internet Explorer and Navigator is a live update mechanism that allows a browser to modify sections of a Web page in the background. Once the page has been modified, the browser reformats it as necessary and displays the changes. Anyone viewing the page sees the updates instantly and doesn't have to wait for the browser to reload the page or access another page. The browser makes the changes without ever having to go back to the Web server for additional content."
In addition to dynamic HTML and other advancements in that area, there are several other tools that were designed to directly compete with HTML. One such tool is Java, which is hailed as a complete programming language, with many features that are compatible with other applications. Another innovation is eXtensible Markup Language (XML) that allows for the standardized exchange of information between computers. XML is being touted as the next big Internet standard, the heir apparent to the HTML throne. It is still an evolving tool that has a maximum potential which remains to be seen. Another tool known as XHTML is also being developed. It is a version of HTML that is based on XML.
Html and Small Business
If a small business owner intends to set up his own Web site, there are several steps to consider. First, the site should be carefully planned out, and its content should be determined. The Web site should be designed by a person with a strong sense of graphic design in order to make it visually appealing for the users. When the site enters the programming phase, a basic knowledge of HTML will come into play. If someone within the company is familiar with HTML, then they could easily do it. If not, a professional programmer should be called upon to lend their expert opinion. This person will then write the code containing the text, graphics, and other aspects of the Web site's structure.
The person doing the implementation of the HTML code should take into consideration the range browsers and browser versions that exist. Since the Web site is a potentially important part of any company with online presence, the references of the programmer should be carefully checked in order to ensure that they know what they are doing. After the programming is done, a host should be chosen for the Web site and then it can finally be promoted in order to attract customers.
Further Reading:
Klein, Leo Robert. "The Joys of Interactivity." Library Journal. January 2000.
Quittner, Joshua. "Network Designer: Tim Berners-Lee. From Thousands of Interconnected Threads of the Internet, He Wove the World Wide Web and Created a Mass Medium for the 21st Century." Time. March 29, 1999.
Stanek, William R. "Creativity and Control." PC Magazine. January, 20, 1998.
See also: Web Site Design
For more information on HTML, visit Britannica.com.
| Meaning | Category |
| Hail To Me Ladies | Miscellaneous->Funnies |
| Hamburger Tomato Mayo And Lettuce | Miscellaneous->Food |
| Hard To Make Love | Miscellaneous->Funnies |
| Harry Took My Lunch! | Miscellaneous->Funnies |
| Hazards Tickle My Larynx | Miscellaneous->Funnies |
| Hello To My Love | Miscellaneous->Funnies |
| Hey That's My Lunch | Miscellaneous->Funnies |
| Hey Too Much Layout | Miscellaneous->Funnies |
| Hey, Try My Language | Miscellaneous->Funnies |
| Hi To My Llama | Miscellaneous->Funnies |
| Hit The Mother Load | Miscellaneous->Funnies |
| Hope Tests Many Lives | Community->Religion |
| Hot Tomatoes Melt Lips | Miscellaneous->Funnies |
| Hyper Text Markup Language | Governmental->Military |
| Hyper Text Multi Language | Academic & Science |
| HyperText Markup Language document | Computing->File Extensions |
| Hypertext Markup Language | Academic & Science->Electronics Computing->Telecom Computing->General Computing->Drivers |
| Hypertext Meta-Language | Governmental->Military |
Click here to submit an acronym.
| HTML (Hypertext Markup Language) | |
|---|---|
| File extension: | .html, .htm |
| MIME type: | text/html |
| Type code: | TEXT |
| Uniform Type Identifier: | public.html |
| Developed by: | World Wide Web Consortium |
| Type of format: | Markup language |
| Extended to: | XHTML |
| Standard(s): | W3C HTML 4.01 W3C HTML 3.2 |
HTML a contraction of Hypertext Markup Language, is the predominant markup language for web pages. It provides a means to describe the structure of text-based information in a document — by denoting certain text as headings, paragraphs, lists, and so on — and to supplement that text with interactive forms, embedded images, and other objects. HTML is written in the form of labels (known as tags), surrounded by angle brackets. HTML can also describe, to some degree, the appearance and semantics of a document, and can include embedded scripting language code which can affect the behavior of web browsers and other HTML processors.
HTML is also often used to refer to content of the MIME type text/html or even more broadly as a generic term for HTML whether in its XML-descended form (such as XHTML 1.0 and later) or its form descended directly from SGML (such as HTML 4.01 and earlier).
In 1980, physicist Tim Berners-Lee, who was an independent contractor at CERN, proposed and prototyped ENQUIRE, a hypertext system for CERN researchers to use to share documents. In 1989, Berners-Lee and CERN data systems engineer Robert Cailliau each submitted separate proposals for an Internet-based hypertext system providing similar functionality. The following year, they collaborated on a joint proposal, the WorldWideWeb (W3) project, [1] which was accepted by CERN.
The first publicly available description of HTML was a document called HTML Tags, first mentioned on the Internet by Berners-Lee in late 1991.[2][3] It describes 22 elements comprising the initial, relatively simple design of HTML. Thirteen of these elements still exist in HTML 4.[4]
Berners-Lee considered HTML to be, at the time, an application of SGML, but it was not formally defined as such until the mid-1993 publication, by the IETF, of the first proposal for an HTML specification: Berners-Lee and Dan Connolly's "Hypertext Markup Language (HTML)" Internet-Draft, which included an SGML Document Type Definition to define the grammar.[5] 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.[6] 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.[7]
After the HTML and HTML+ drafts expired in early 1994, the IETF created an HTML Working Group, which in 1995 completed "HTML 2.0", the first HTML specification intended to be treated as a standard against which future implementations should be based.[6] Published as Request for Comments 1866, HTML 2.0 included ideas from the HTML and HTML+ drafts.[8] There was no "HTML 1.0"; the 2.0 designation was intended to distinguish the new edition from previous drafts.[9]
Further development under the auspices of the IETF was stalled by competing interests. Since 1996, the HTML specifications have been maintained, with input from commercial software vendors, by the World Wide Web Consortium (W3C).[7] However, in 2000, HTML also became an international standard (ISO/IEC 15445:2000). The last HTML specification published by the W3C is the HTML 4.01 Recommendation, published in late 1999. Its issues and errors were last acknowledged by errata published in 2001.
| HTML |
|---|
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Character encodings |
July, 1993: Hypertext Markup Language,was published at IETF working draft (that is: not a standard – yet).
November, 1995: HTML 2.0 published as IETF Request for Comments:
ultimately all were declared obsolete/historic by RFC 2854 in June 2000.
An HTML 3.0 standard was proposed to the IETF by Dave Raggett and the newly formed W3C in April 1995. It proposed 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 math elements.[10] Even though it was designed to be compatible with HTML 2.0, it was too complex at the time to be implemented. Browser vendors opted to support only parts of the proposal, but implemented other markup constructs that they wanted to be incorporated into the standard.[11] When the draft expired in September 1995, work in this direction was discontinued due to lack of browser support. HTML 3.1 was never officially proposed, and the next standard proposal was HTML 3.2 (code-named "Wilbur"), which dropped the majority of the new features in HTML 3.0 and instead adopted many browser-specific element types and attributes that had been created for the Netscape and Mosaic web browsers.[12]
January 14, 1997: HTML 3.2, published as a W3C Recommendation.
HTML 3.2 was never submitted to the IETF, whose HTML Working Group closed in September 1996;[13] it was instead published as one of the W3C's first "Recommendations" in early 1997. Math support as proposed by HTML 3.0 finally came about years later with a different standard, MathML.
December 18, 1997: HTML 4.0, published as a W3C Recommendation. It offers three "flavors":
HTML 4.0 (initially code-named "Cougar")[12] likewise adopted many browser-specific element types and attributes, but at the same time began to try to "clean up" the standard by marking some of them as deprecated, and suggesting they not be used. Minor editorial revisions to the HTML 4.0 specification were published as HTML 4.01.
December 24, 1999: HTML 4.01, published as a W3C Recommendation. It offers the same three flavors as HTML 4.0, and its last errata was published May 12, 2001.
HTML 4.01 and ISO/IEC 15445:2000 are the most recent and final versions of HTML.
May 15, 2000: ISO/IEC 15445:2000 ("ISO HTML", based on HTML 4.01 Strict), published as an ISO/IEC international standard.
HTML 5 is still an Editor’s Draft, and not endorsed by W3C yet.
XHTML is a separate language that began as a reformulation of HTML 4.01 using XML 1.0. It continues to be developed:
HTML markup consists of several types of entities, including: elements, attributes, data types and character references.
In order to enable Document Type Definition (DTD)-based validation with SGML tools and in order to avoid the Quirks mode in browsers, all HTML documents should start with a Document Type Declaration (informally, a "DOCTYPE"). The DTD contains machine readable grammar specifying the permitted and prohibited content for a document conforming to such a DTD. Browsers do not direct to the page in the DTD, however. Browsers only look at the doctype in order to decide the layout mode. Not all doctypes trigger the Standards layout mode avoiding the Quirks mode. For example:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">This declaration references the Strict DTD of HTML 4.01, which does not have presentational elements like <font>, leaving formatting to Cascading Style Sheets and the span and div tags. SGML-based validators read the DTD in order to properly parse the document and to perform validation. In modern browsers, the HTML 4.01 Strict doctype activates the Standards layout mode for CSS as opposed to the Quirks mode.
In addition, HTML 4.01 provides Transitional and Frameset DTDs. The Transitional DTD was intended to gradually phase in the changes made in the Strict DTD, while the Frameset DTD was intended for those documents which contained frames.
Elements are the basic structure for HTML markup. Elements have two basic properties: attributes and content. Each attribute
and each element's content has certain restrictions that must be followed for an HTML document to be considered valid. An element
usually has a start label (e.g. <label>) and an end label (e.g. </label>). The element's
attributes are contained in the start label and content is located between the labels (e.g.
<label attribute="value">Content</label>). Some elements, such as <br>, do not
have any content and so need no closing label. Listed below are several types of markup elements used in HTML.
Structural markup describes the purpose of text. For example, <h2>Golf</h2> establishes "Golf"
as a second-level heading, which would be rendered in a browser in a manner similar
to the "HTML markup" title at the start of this section. Structural markup does not denote any specific rendering, but most web
browsers have standardized on how elements should be formatted. Further styling should be done with Cascading Style Sheets (CSS).
Presentational markup describes the appearance of the text, regardless of its function. For example
<b>boldface</b> indicates that visual output devices should render "boldface" in bold
text, but gives no indication what devices which are unable to do this (such as aural devices that read the text aloud) should
do. In the case of both <b>bold</b> and <i>italic</i> there are
elements which usually have an equivalent visual rendering but are more semantic in nature, namely
<strong>strong emphasis</strong> and
<em>emphasis</em> 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 4.0 specification, in favor of
CSS based style design.
Hypertext markup links parts of the document to other documents. HTML up through version XHTML 1.1 requires the use of an anchor element to create a hyperlink in the flow of text:
<a>Wikipedia</a>. However, the href attribute must also be set to a valid URL so for example the HTML code, <a
href="http://en.wikipedia.org/">Wikipedia</a>, will render the word "Wikipedia" as a hyperlink.
The attributes of an element are name-value pairs, separated by "=", and written within the start label of an element, after the element's name. The value should be enclosed in single or double quotes, although values consisting of certain characters can be left unquoted in HTML (but not XHTML).[14][15] Leaving attribute values unquoted is considered unsafe.[16]
Most elements take any of several common attributes: id, class, style and
title. Most also take language-related attributes: lang and dir.
The id attribute provides a document-wide unique identifier for an element. This can be used by stylesheets to
provide presentational properties, by browsers to focus attention on the specific element or by scripts to alter the contents or
presentation of an element. The class attribute provides a way of classifying similar elements for presentation
purposes. For example, an HTML document (or a set of documents) may use the designation class="notation" to indicate
that all elements with this class value are all subordinate to the main text of the document (or documents). Such notation
classes of elements might be gathered together and presented as footnotes on a page, rather than appearing in the place where
they appear in the source HTML.
An author may use the style non-attributal codes presentational properties to a particular element. It is
considered better practice to use an element’s son- id page and select the element with a stylesheet, though
sometimes this can be too cumbersome for a simple ad hoc application of styled properties. The title is used to
attach subtextual explanation to an element. In most browsers this title attribute is displayed as what is often
referred to as a tooltip. The generic inline span element can be used to
demonstrate these various non-attributes.
<span id='anId' class='aClass' style='color:red;' title='Hypertext Markup Language'>HTML</span>The preceding displays as HTML (pointing the cursor at the abbreviation should display the title text in most browsers).
As of version 4.0, 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 equivalent are considered equivalent and are rendered identically.
The ability to "escape" characters in this way allows for the characters "<" and "&" (when written as
< and &, respectively) to be interpreted as character data, rather than markup. For
example, a literal "<" normally indicates the start of a label, and "&" normally indicates the start of a character entity
reference or numeric character reference; writing it as "&" or "&" or "&" allows "&" to be included
in the content of elements or the values of attributes. The double-quote character, ", when used to quote an attribute value,
must also be escaped as """ or """ or """ when it appears within in the attribute value itself.
However, since document authors often overlook the need to escape these characters, browsers tend to be very forgiving, treating
them as markup only when subsequent text appears to confirm that intent.
Escaping also allows for characters that are not easily typed or that aren't even available in the document's character encoding to be represented within the element and attribute content. For example, "é", a
character typically found only on Western European keyboards, can be written in any HTML document as the entity reference
é or as the numeric references é or é. The characters
comprising those references (that is, the "&", the ";", the letters in "eacute", and so on) are available on all
keyboards[citation needed] and are supported in all character encodings, whereas the literal "é" is
not.
HTML also defines several data types for element content, such as script data and stylesheet data, and a plethora of types for attribute values, including IDs, names, URIs, numbers, units of length, languages, media descriptors, colors, character encodings, dates and times, and so on. All of these data types are specializations of character data.
There is no official specification called "Semantic HTML", though the strict flavors of HTML discussed below are a push in that direction. Rather, semantic HTML refers to an objective and a practice
to create documents with HTML that contain only the author's intended meaning, without any reference to how this meaning is
presented or conveyed. A classic example is the distinction between the emphasis element (<em>) and the
italics element (<i>). Often the emphasis element is displayed in italics, so the presentation is typically
the same. However, emphasizing something is different from listing the title of a book, for example, which may also be displayed
in italics. In purely semantic HTML, a book title would use a separate element than emphasized text uses (for example a
<span>), because they are each meaningfully different things.
The goal of semantic HTML requires two things of authors:
<cite class="booktitle">The Grapes of
Wrath</cite>. Here, the <cite> element is used, because it most closely matches the meaning of
this phrase in the text. However, the <cite> element is not specific enough to this task because we mean to
cite specifically a book title as opposed to a newspaper article or a particular academic journal.Semantic HTML also requires complementary specifications and software compliance with these specifications. Primarily, the
development and proliferation of CSS has led to increasing support for semantic
HTML because CSS provides designers with a rich language to alter the presentation of semantic-only documents. With the
development of CSS the need to include presentational properties in a document has virtually disappeared. With the advent and
refinement of CSS and the increasing support for it in web browsers, subsequent editions of HTML increasingly stress only using
markup that suggests the semantic structure and phrasing of the document, like headings, paragraphs, quotes, and lists, instead
of using markup which is written for visual purposes only, like <font>, <b> (bold), and
<i> (italics). Some of these elements are not permitted in certain varieties of HTML, like HTML 4.01 Strict.
CSS provides a way to separate document semantics from the content's presentation, by keeping everything relevant to presentation
defined in a CSS file. See separation of style and content.
Semantic HTML offers many advantages. First, it ensures consistency in style across elements that have the same meaning. Every heading, every quotation, every similar element receives the same presentation properties.
Second, semantic HTML frees authors from the need to concern themselves with presentation details. When writing the number two, for example, should it be written out in words ("two"), or should it be written as a numeral (2)? A semantic markup might enter something like <number>2</number> and leave presentation details to the stylesheet designers. Similarly, an author might wonder where to break out quotations into separate indented blocks of text - with purely semantic HTML, such details would be left up to stylesheet designers. Authors would simply indicate quotations when they occur in the text, and not concern themselves with presentation.
A third advantage is device independence and repurposing of documents. A semantic HTML document can be paired with any number of stylesheets to provide output to computer screens (through web browsers), high-resolution printers, handheld devices, aural browsers or braille devices for those with visual impairments, and so on. To accomplish this nothing needs to be changed in a well coded semantic HTML document. Readily available stylesheets make this a simple matter of pairing a semantic HTML document with the appropriate stylesheets (of course, the stylesheet's selectors need to match the appropriate properties in the HTML document).
Some aspects of authoring documents make separating semantics from style (in other words, meaning from presentation) difficult. Some elements are hybrids, using presentation in their very meaning. For example, a table displays content in a tabular form. Often this content only conveys the meaning when presented in this way. Repurposing a table for an aural device typically involves somehow presenting the table as an inherently visual element in an audible form. On the other hand, we frequently present lyrical songs — something inherently meant for audible presentation — and instead present them in textual form on a web page. For these types of elements, the meaning is not so easily separated from their presentation. However, for a great many of the elements used and meanings conveyed in HTML the translation is relatively smooth.
HTML documents can be delivered by the same means as any other computer file; however, HTML documents are most often delivered in one of the following two forms: Over HTTP servers and through email.
The World Wide Web is primarily composed of HTML documents transmitted from a web server to a web browser using the Hypertext Transfer Protocol (HTTP). However, HTTP can be used to serve images, sound and other content in addition to HTML. To allow the web browser to know how to handle the document it received, an indication of the file format of the document must be transmitted along with the document. This vital metadata includes the MIME type (text/html for HTML 4.01 and earlier, application/xhtml+xml for XHTML 1.0 and later) and the character encoding (see Character encodings in HTML).
In modern browsers, the MIME type that is sent with the HTML document affects how the document is interpreted. A document sent with an XHTML MIME type, or served as application/xhtml+xml, is expected to be well-formed XML and a syntax error causes the browser to fail to render the document. The same document sent with a HTML MIME type, or served as text/html, might get displayed since web browsers are more lenient with HTML. However, XHTML parsed this way is not considered either proper XHTML nor HTML, but so-called tag soup.
If the MIME type is not recognized as HTML, the web browser should not attempt to render the document as HTML, even if the document is prefaced with a correct Document Type Declaration. Nevertheless, some web browsers do examine the contents or URL of the document and attempt to infer the file type, despite this being forbidden by the HTTP 1.1 specification.
Most graphical e-mail clients allow the use of a subset of HTML (often ill-defined) to provide formatting and semantic markup capabilities not available with plain text, like emphasized text, block quotations for replies, and diagrams or mathematical formulas that couldn't easily be described otherwise. Many of these clients include both a GUI editor for composing HTML e-mails and a rendering engine for displaying received HTML e-mails. Use of HTML in e-mail is controversial due to compatibility issues, because it can be used in phishing/privacy attacks, because it can confuse spam filters, and because the message size is larger than plain text.
The most common filename extension for files containing HTML is .html. A common abbreviation of this is .htm; it originates from older operating systems and file systems, such as the DOS versions from the 80's and early 90's and FAT, which limit file extensions to three letters. Both forms are widely supported by browsers.
Since its inception HTML and its associated protocols gained acceptance relatively quickly. However, no clear standards existed in the early years of the language. Though its creators originally conceived of HTML as a semantic language devoid of presentation details, practical uses pushed many presentational elements and attributes into the language: driven largely by the various browser vendors. The latest standards surrounding HTML reflect efforts to overcome the sometimes chaotic development of the language and to create a rational foundation to build both meaningful and well-presented documents. To return HTML to its role as a semantic language, the W3C has developed style languages such as CSS and XSL to shoulder the burden of presentation. In conjunction the HTML specification has slowly reined in the presentational elements within the specification.
There are two axes differentiating various flavors of HTML as currently specified: SGML-based HTML versus XML-based HTML (referred to as XHTML) on the one axis and strict versus transitional (loose) versus frameset on the other axis.
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 clearly distinguish it from the more traditional definition; however, the root element name continues to be 'html' even in the XHTML-specified HTML. The W3C intended XHTML 1.0 to be identical to HTML 4.01 except where limitations of XML over the more complex SGML require workarounds. Because XHTML and HTML are closely related, sometimes they are documented in parallel. In such circumstances some authors conflate the two names as (X)HTML or X(HTML).[17]
Like HTML 4.01, XHTML 1.0 has three sub-specifications: strict, loose and frameset.
Aside from the different opening declarations for a document, the differences between an HTML 4.01 and XHTML 1.0 document — in
each of the corresponding DTDs — is largely syntactic. The underlying syntax of HTML allows many shortcuts that XHTML does not,
such as elements with optional opening or closing tags, and even EMPTY elements which must not have an end tag. By contrast,
XHTML requires all elements to have an opening tag or a closing tag. XHTML, however, also introduces a new shortcut: an XHTML tag
may be opened and closed within the same tag, by including a slash before the end of the tag like this: <br/>.
The introduction of this short-hand, undefined in any HTML 4.01 DTD, may confuse earlier software unfamiliar with this new
convention.
To understand the subtle differences between HTML and XHTML consider the transformation of a valid and well-formed XHTML 1.0 document into a valid and well-formed HTML 4.01 document. To make this translation requires the following steps:
lang attribute rather than the XHTML
xml:lang attribute XHTML uses XML's built in language defining functionality attribute.xmlns=URI). HTML has no facilities for namespaces.<?xml version="1.0"
encoding="utf-8"?>).<meta> element within the HTML.<br/> to
<br>)Those are the main changes necessary to translate a document from XHTML 1.0 to HTML 4.01. To translate from HTML to XHTML would also require the addition of any omitted opening or closing tags. Whether coding in HTML or XHTML it may just be best to always include the optional labels within an HTML document rather than remembering which labels can be omitted.
A well-formed XHTML document adheres to all the syntax requirements of XML. A valid document adheres to the content specification for XHTML, which describes the document structure.
The W3C recommends several conventions to ensure an easy migration between HTML and XHTML (see HTML Compatibility Guidelines). The following steps can be applied to XHTML 1.0 documents only:
xml:lang and lang attributes on any elements assigning language.<br /> instead of
<br/><img></img>", not "<img />" )Note that by carefully following the W3C’s compatibility guidelines, a user agent should be able to interpret the document equally as HTML or XHTML. For documents which are XHTML 1.0 and have been made compatible in this way, the W3C permits them to the served either as HTML (with a text/html) MIME type), or as XHTML (with an application/xhtml+xml or application/xml MIME type). When delivered as XHTML, browsers should use an XML parser, which adheres strictly to the XML specifications for parsing the document's contents.
The latest SGML-based specification HTML 4.01 and the earliest XHTML version include three sub-specifications: Strict, Transitional (once called Loose), and Frameset. The Strict variant represents the standard proper, whereas the Transitional and Frameset variants were developed to assist in the transition from earlier versions of HTML (including HTML 3.2). The Transitional and Frameset variants allow for presentational markup whereas the Strict variant encourages the use of style sheets through its omission of most presentational markup.
The primary differences which make the Transitional variant more permissive than the Strict variant (the differences as the same in HTML 4 and XHTML 1.0) are:
body, blockquote,
form, noscript and noframesu)s and strike)centerfontbasefontbackground and bgcolor attributes for body element.align attribute on div, form, paragraph (p), and heading
(h1...h6) elementsalign, noshade, size, and width attributes on hr
elementalign, border, vspace, and hspace attributes on img and
object elementsalign attribute on legend and caption elementsalign and bgcolor on table elementnowrap, bgcolor, width, height on td and th
elementsbgcolor attribute on tr elementclear attribute on br elementcompact attribute on dl, dir and menu elementstype, compact, and start attributes on ol and ul
elementstype and value attributes on li elementwidth attribute on pre elementmenu list (no substitute, though unordered list is recommended; may return in XHTML 2.0 specification)dir list (no substitute, though unordered list is recommended)isindex (element requires server-side support and is typically added to documents server-side)applet (deprecated in favor of object element)pre element does not allow: applet, font, and basefont (elements not defined in strict DTD)language attribute on script element (presumably redundant with type attribute, though
this is maintained for legacy reasons).frameset element (used in place of body for frameset DTD)frame elementiframenoframestarget attribute on anchor, client-side image-map (imagemap), link,
form, and base elementsIn addition to the above transitional differences, the frameset specifications (whether XHTML 1.0 or HTML 4.01) specifies a different content model: <source lang="html4strict"> <html>
<head> Any of the various head related elements. </head>
<frameset> <frame></frame>
<noframes></noframes> </frameset>
</html> </source>
As this list demonstrates, the loose flavors of the specification are maintained for legacy support. However, contrary to popular misconceptions, the move to XHTML does not imply a removal of this legacy support. Rather the X in XML stands for extensible and the W3C is modularizing the entire specification and opening it up to independent extensions. The primary achievement in the move from XHTML 1.0 to XHTML 1.1 is the modularization of the entire specification. The strict version of HTML is deployed in XHTML 1.1 through a set of modular extensions to the base XHTML 1.1 specification. Likewise someone looking for the loose (transitional) or frameset specifications will find similar extended XHTML 1.1 support (much of it is contained in the legacy or frame modules). The modularization also allows for separate features to develop on their own timetable. So for example XHTML 1.1 will allow quicker migration to emerging XML standards such as MathML (a presentational and semantic math language based on XML) and XForms — a new highly advanced web-form technology to replace the existing HTML forms.
In summary, the HTML 4.01 specification primarily reined in all the various HTML implementations into a single clear written specification based on SGML. XHTML 1.0, ported this specification, as is, to the new XML defined specification. Next, XHTML 1.1 takes advantage of the extensible nature of XML and modularizes the whole specification. XHTML 2.0 will be the first step in adding new features to the specification in a standards-body-based approach.
HTML lacks some of the features found in earlier hypertext systems, such as typed links, transclusion, source tracking, fat links, and more.[18] Even some hypertext features that were in early versions of HTML have been ignored by most popular web browsers until recently, such as the link element and in-browser Web page editing.
Sometimes Web services or browser manufacturers remedy these shortcomings. For instance, members of the modern social software landscape such as wikis and content management systems allow surfers to edit the Web pages they visit.
| Standards of the World Wide Web Consortium | |
|---|---|
| Recommendations | CSS · CGI · DOM · HTML · RDF · SVG · SOAP · SMIL · SRGS · SSML · VoiceXML · WSDL · XACML · XHTML · XML · XML Events · XForms · XML Information Set · XML Schema (W3C) · XPath · XQuery · XSL Transformations · XLink · XML Base · SISR · OWL · MathML · RDF Schema · Timed Text · |
| Notes | |
| Working Drafts | CURIE · CCXML · InkML ·
XFrames · XFDL · Web Integration Compound Document ·
|
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
Dansk (Danish)
n. - hypertext markup language; Internetsprog
Français (French)
n. - (Comput) langage additif d'hypertexte
Deutsch (German)
n. - (Comp.) HTML-Sprache
Ελληνική (Greek)
abbr. - (Η/Υ) γλώσσα σήμανσης υπερκειμένου
Español (Spanish)
n. - lenguaje de marcado de hipertexto
Svenska (Swedish)
abbr. - hypertext markup language (data)
中文(简体) (Chinese (Simplified))
超文字标记语言
中文(繁體) (Chinese (Traditional))
n. - 超文字標記語言
한국어 (Korean)
n. - hypertext mark up language
العربيه (Arabic)
(اختصار) لغه برمجه للأنترنت
עברית (Hebrew)
n. - שפת שימוש באינטרנט
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