Acronyms, initialisms, and alphabetisms are abbreviations that are formed using the initial components in a phrase or name. These components may be individual letters or parts of words .... of HyperText Markup Language, is the predominant markup language
Markup language
A markup language is a set of codes that give instructions regarding the structure of a text or how it is to be displayed. Markup languages have been in use for centuries, and in recent years have been used in computer typesetting and word-processing systems to specify the formatting, layout, structure, and other elements of a document.... for Web page
Web page
A web page or webpage is a resource of information that is suitable for the World Wide Web and can be accessed through a web browser.This information is usually in HyperText Markup Language or eXtensible HyperText Markup Language format, and may provide Navigation bar to other web pages via hypertext Hyperlink.... s. It provides a means to describe the structure of text-based information in a document—by denoting certain text as links, 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 tags, surrounded by angle brackets.
Acronyms, initialisms, and alphabetisms are abbreviations that are formed using the initial components in a phrase or name. These components may be individual letters or parts of words .... of HyperText Markup Language, is the predominant markup language
Markup language
A markup language is a set of codes that give instructions regarding the structure of a text or how it is to be displayed. Markup languages have been in use for centuries, and in recent years have been used in computer typesetting and word-processing systems to specify the formatting, layout, structure, and other elements of a document.... for Web page
Web page
A web page or webpage is a resource of information that is suitable for the World Wide Web and can be accessed through a web browser.This information is usually in HyperText Markup Language or eXtensible HyperText Markup Language format, and may provide Navigation bar to other web pages via hypertext Hyperlink.... s. It provides a means to describe the structure of text-based information in a document—by denoting certain text as links, 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 tags, surrounded by angle brackets. HTML can also describe, to some degree, the appearance and semantics
Semantics
Semantics is the study of meaning in communication. The word is derived from the Greek language word s??a?t???? , "significant", from s??a??? , "to signify, to indicate" and that from s??a , "sign, mark, token".... of a document, and can include embedded scripting language
Scripting language
A scripting language, script language or extension language, is a programming language that allows some control of a single or many Application software.... code (such as JavaScript
JavaScript
JavaScript is a scripting language widely used for client-side web development. It was the originating Programming language dialect of the ECMAScript standard.... ) which can affect the behavior of Web browser
Web browser
A Web browser is a application software which enables a user to display and interact with text, images, videos, music, games and other information typically located on a Web page at a website on the World Wide Web or a local area network.... s and other HTML processors.
Sir Timothy John Berners-Lee, Order of Merit, Order of the British Empire, Royal Society, Royal Academy of Engineering, Royal Society of Arts is an English people computer scientist and MIT professor credited with inventing the World Wide Web.... , who was an independent contractor at CERN
CERN
The European Organization for Nuclear Research , known as CERN , , is the world's largest particle physics laboratory, situated in the northwest suburbs of Geneva on the France-Switzerland border, established in 1954 in science.... , proposed and prototyped ENQUIRE
ENQUIRE
ENQUIRE was an early project of Tim Berners-Lee, who went on to create the World Wide Web in 1989. ENQUIRE had some of the same ideas as the Web and the Semantic Web but was different in several important ways, one of them that it was not supposed to be released to the general public.... , a system for CERN
CERN
The European Organization for Nuclear Research , known as CERN , , is the world's largest particle physics laboratory, situated in the northwest suburbs of Geneva on the France-Switzerland border, established in 1954 in science.... researchers to use and share documents. In 1989, Berners-Lee and CERN data systems engineer Robert Cailliau
Robert Cailliau
Robert Cailliau is a Belgian computer scientist who, together with Tim Berners-Lee, Software developer the World Wide Web.... each submitted separate proposals for an Internet
Internet
The Internet is a global network of interconnected computers, enabling users to share information along multiple channels. Typically, a computer that connects to the Internet can access information from a vast array of available server and other computers by moving information from them to the computer's local memory.... -based hypertext
Hypertext
Hypertext is text, displayed on a computer, with references to other text that the reader can immediately follow, usually by a mouse click or keypress sequence.... system providing similar functionality. The following year, they collaborated on a joint proposal, the WorldWideWeb (W3) project,
which was accepted by CERN.
First specifications
The first publicly available description of HTML was a document called HTML Tags, first mentioned on the Internet by Berners-Lee in late 1991. It describes 22 elements comprising the initial, relatively simple design of HTML. Thirteen of these elements still exist in HTML 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
Internet Engineering Task Force
The Internet Engineering Task Force develops and promotes Internet standards, cooperating closely with the World Wide Web Consortium and International Organization for Standardization/International Electrotechnical Commission standard bodies and dealing in particular with standards of the TCP/IP and Internet protocol suite.... , of the first proposal for an HTML specification: Berners-Lee and Dan Connolly
Dan Connolly
Dan Connolly received a B.S. in Computer Science from the University of Texas at Austin in 1990. His research interests include investigating the value of formal descriptions of chaotic systems like the Web, particularly in the consensus-building process, and the Semantic Web.... 's , which included an SGML Document Type Definition
Document Type Definition
Document Type Definition is one of several SGML and XML schema languages, and is also the term used to describe a document or portion thereof that is authored in the DTD language.... to define the grammar. The draft expired after six months, but was notable for its acknowledgment of the NCSA Mosaic
Mosaic (web browser)
Mosaic is the web browser credited with popularizing the World Wide Web. It was also a client for earlier protocols such as FTP, Usenet, and Gopher .... 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 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. Published as Request for Comments
Request for Comments
In computer network engineering, a request for comments is a memorandum published by the Internet Engineering Task Force describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems.... 1866, HTML 2.0 included ideas from the HTML and HTML+ drafts. There was no "HTML 1.0"; the 2.0 designation was intended to distinguish the new edition from previous drafts.
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
World Wide Web Consortium
The World Wide Web Consortium is the main international standards organization for the World Wide Web . It is arranged as a consortium where member organizations maintain full-time staff for the purpose of working together in the development of standards for the World Wide Web.... (W3C). However, in 2000, HTML also became an international standard (ISO
International Organization for Standardization
The International Organization for Standardization , widely known as ISO , is an international standard-setting body composed of representatives from various national standards organizations.... /IEC
International Electrotechnical Commission
The International Electrotechnical Commission is a Non-profit organization, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies ? collectively known as "electrotechnology".... 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.
Version history of the standard
HTML version timeline
November 1995: HTML 2.0 was published as IETF RFC 1866. Supplemental RFC
Request for Comments
In computer network engineering, a request for comments is a memorandum published by the Internet Engineering Task Force describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems.... s added capabilities:
In computing, internationalization and localization are means of adapting computer software to different languages and regional differences. Internationalization is the process of designing a software application so that it can be adapted to various languages and regions without engineering changes.... )
In June 2000, all of these were declared obsolete/historic by RFC 2854.
A W3C Recommendation is the final stage of a ratification process of the World Wide Web Consortium working group concerning the standard. This designation signifies that a document has been subjected to a public and W3C-member organization's review.... . It was the first version developed and standardized exclusively by the W3C, as the IETF had closed its HTML Working Group in September 1997.
HTML 3.2 dropped math formulas entirely, reconciled overlap among various proprietary extensions, and adopted most of Netscape's visual markup tags. Netscape's blink element and Microsoft's marquee element were omitted due to a mutual agreement between the two companies. The ability to include mathematical formulas in HTML wasn't standardized until years later in MathML
MathML
Mathematical Markup Language is an application of XML for describing mathematics notations and capturing both its structure and content. It aims at integrating mathematical formulae into World Wide Web documents.... .
December 1997: HTML 4.0 was published as a W3C Recommendation. It offers three "flavors":
Strict, in which deprecated elements are forbidden,
Transitional, in which deprecated elements are allowed,
On a web page, framing means that a website can be organized into HTML element#Frames. Each frame displays a different HTML document. Headers and sidebar menus do not move when the content frame is scrolled up and down.... related elements are allowed;
Initially code-named "Cougar", 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
Deprecation
In computer software standards and documentation, the term deprecation is applied to software features that are superseded and should be avoided.... in favor of style sheets.
April 1998: HTML 4.0 was reissued with minor edits without incrementing the version number.
December 1999: HTML 4.01 was published as a W3C Recommendation. It offers the same three flavors as HTML 4.0, and its last were published May 12, 2001.
The International Organization for Standardization , widely known as ISO , is an international standard-setting body composed of representatives from various national standards organizations.... HTML", based on HTML 4.01 Strict) was published as an ISO/IEC international standard.
As of mid-2008, HTML 4.01 and ISO/IEC 15445:2000 are the most recent versions of HTML. Development of the parallel, XML-based language XHTML occupied the W3C's HTML Working Group through the early and mid-2000s.
Drafts
October 1991: HTML Tags, an informal CERN document listing twelve HTML tags, was first mentioned in public. November 1992.
July 1993: Hypertext Markup Language was published by the IETF
Internet Engineering Task Force
The Internet Engineering Task Force develops and promotes Internet standards, cooperating closely with the World Wide Web Consortium and International Organization for Standardization/International Electrotechnical Commission standard bodies and dealing in particular with standards of the TCP/IP and Internet protocol suite.... as an Internet-Draft (a rough proposal for a standard). It expired in January 1994.
November 1993: HTML+ was published by the IETF as an Internet-Draft and was a competing proposal to the Hypertext Markup Language draft. It expired in May 1994.
April 1995 (authored March 1995): HTML 3.0 was proposed as a standard to the IETF, but the proposal expired five months later 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.
A demonstration appeared in W3C's own Arena browser
Arena (web browser)
Arena is a web browser developed by the W3C for testing support for HTML and Cascading Style Sheets.The W3C halted work on the Arena browser, and switched to the Amaya browser as their new testbed.... . HTML 3.0 did not succeed for several reasons. The pace of browser development, as well as the number of interested parties, had outstripped the resources of the IETF. Netscape continued to introduce HTML elements that specified the visual appearance of documents, contrary to the goals of the newly-formed W3C, which sought to limit HTML to describing logical structure. Microsoft, a newcomer at the time, played to all sides by creating its own tags, implementing Netscape's elements for compatibility, and supporting W3C features such as Cascading Style Sheets.
January 2008: HTML5 was published as a Working Draft by the W3C.
XHTML versions
XHTML is a separate language that began as a reformulation of HTML 4.01 using XML 1.0. It continues to be developed:
XHTML 1.0, published January 26, 2000 as a W3C Recommendation, later revised and republished August 1, 2002. It offers the same three flavors as HTML 4.0 and 4.01, reformulated in XML, with minor restrictions.
XHTML 1.1, published May 31, 2001 as a W3C Recommendation. It is based on XHTML 1.0 Strict, but includes minor changes, can be customized, and is reformulated using modules from , which was published April 10, 2001 as a W3C Recommendation.
XHTML 2.0, is still a W3C Working Draft. XHTML 2.0 is incompatible with XHTML 1.x and, therefore, would be more accurate to characterize as an XHTML-inspired new language than an update to XHTML 1.x.
XHTML5, which is an update to XHTML 1.x, is being defined alongside HTML5 in the HTML5 draft.
HTML markup
HTML markup consists of several key components, including elements (and their attributes), character-based data types, and character references and entity references. Another important component is the document type declaration
Document Type Declaration
A Document Type Declaration, or DOCTYPE, is an instruction that associates a particular SGML or XML document with a Document Type Definition .... , which specifies the Document Type Definition
Document Type Definition
Document Type Definition is one of several SGML and XML schema languages, and is also the term used to describe a document or portion thereof that is authored in the DTD language.... . As of HTML 5
HTML 5
HTML 5 is the fifth major revision of the core language of the World Wide Web, HTML. HTML 5 specifies two variants of the same language, a "classic" HTML variant known as HTML 5 and an XHTML variant known as XHTML 5.... , no Document Type Definition will need to be specified, and will only determine the layout mode.
A "Hello World" program is a computer program that prints out "Hello world!" on a display device. It is used in many introductory tutorials for teaching a programming language.... , a common computer program
Computer program
Computer programs are Instruction for a computer. A computer requires programs to function. Moreover, a computer program does not run unless its instructions are executed by a Central processing unit; however, a program may communicate an Algorithm#Formalization of algorithms to people without running.... employed for comparing programming language
Programming language
A programming language is a machine-readable artificial language designed to express computations that can be performed by a machine, particularly a computer.... s, scripting language
Scripting language
A scripting language, script language or extension language, is a programming language that allows some control of a single or many Application software.... s, and markup language
Markup language
A markup language is a set of codes that give instructions regarding the structure of a text or how it is to be displayed. Markup languages have been in use for centuries, and in recent years have been used in computer typesetting and word-processing systems to specify the formatting, layout, structure, and other elements of a document.... s is made of 9 lines of code in HTML, albeit line break
Line break
Line break may refer to:*Line break , a literary device*Soft return, a wrapping of a line of text*Newline, an indicator of the end of a line of text... s and the tag, or the document type declaration
Document Type Declaration
A Document Type Declaration, or DOCTYPE, is an instruction that associates a particular SGML or XML document with a Document Type Definition .... , are optional:
Hello HTML
Hello World!!
This Document Type Declaration is in HTML5 format.
If the tag is not included, the layout mode defaults to "quirks mode
Quirks mode
Quirks mode refers to a technique used by some web browsers for the sake of maintaining backward compatibility with web pages designed for older browsers, instead of strictly complying with World Wide Web Consortium and Internet Engineering Task Force standards in standards mode.... ."
In computing, an HTML element indicates structure in an HTML document and a way of hierarchically arranging content. More specifically, an HTML element is an Standard Generalized Markup Language element that meets the requirements of one or more of the HTML Document Type Definitions .... s for more detailed descriptions.
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 a HTML document to be considered valid. An element usually has a start tag (e.g. ) and an end tag (e.g. ). The element's attributes are contained in the start tag and content is located between the tags (e.g. Content). Some elements, such as , do not have any content and must not have a closing tag. Listed below are several types of markup elements used in HTML.
Structural markup describes the purpose of text. For example,
selfref|For Wikipedia's headings guideline, see... , 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. Text may be further styled with Cascading Style Sheets
Cascading Style Sheets
Cascading Style Sheets is a stylesheet language used to describe the presentation of a document written in a markup language. Its most common application is to style web pages written in HTML and XHTML, but the language can be applied to any kind of XML document, including Scalable Vector Graphics and XUL.... (CSS).
Presentational markup describes the appearance of the text, regardless of its function. For example boldface 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 bold and italic, there are elements which usually have an equivalent visual rendering but are more semantic in nature, namely strong emphasis and emphasis 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
Deprecation
In computer software standards and documentation, the term deprecation is applied to software features that are superseded and should be avoided.... under the HTML 4.0 specification, in favor of CSS
Cascading Style Sheets
Cascading Style Sheets is a stylesheet language used to describe the presentation of a document written in a markup language. Its most common application is to style web pages written in HTML and XHTML, but the language can be applied to any kind of XML document, including Scalable Vector Graphics and XUL.... based style design.
Hypertext markup links parts of the document to other documents. HTML up through version XHTML
XHTML
The Extensible Hypertext Markup Language, or XHTML, is a markup language that has the same depth of expression as HTML, but also conforms to XML syntax.... 1.1 requires the use of an anchor element to create a hyperlink in the flow of text: Wikipedia. However, the href attribute must also be set to a valid URL
Uniform Resource Locator
In Information technology, a Uniform Resource Locator is a type of Uniform Resource Identifier that specifies where an identified resource is available and the mechanism for retrieving it.... so for example the HTML code, Wikipedia, will render the word "" as a hyperlink
Hyperlink
In computing, a hyperlink, usually shortened to link, is a directly followable reference within a hypertext document.The area from which the hyperlink can be activated is called its anchor; its target is what the link points to, which may be another location within the same page or document, another page or document, or a... .To link on an image, the anchor tag use the following syntax:
Attributes
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 (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).
Most elements can take any of several common attributes:
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 might use the designation class="notation" to indicate that all elements with this class value are subordinate to the main text of the document. 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.
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 attribute is used to attach subtextual explanation to an element. In most browsers this attribute is displayed as what is often referred to as a tooltip
Tooltip
The tooltip is a common graphical user interface element. It is used in conjunction with a cursor , usually a mouse pointer. The user hovers the cursor over an item, without clicking it, and a small "hover box" appears with supplementary information regarding the item being hovered over.... .
The generic inline element span can be used to demonstrate these various attributes:
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 also take the language-related attributes lang and dir.
In the markup languages SGML, HTML, XHTML and XML, a character entity reference is a reference to a particular kind of named SGML entity that has been predefined or explicitly declared in a Document Type Definition .... s and a set of 1,114,050 numeric character reference
Numeric character reference
A numeric character reference is a common markup construct used in SGML and other SGML-based markup languages such as HTML and XML. It consists of a short sequence of character s that, in turn, represent a single character from the Universal Character Set of Unicode.... s, 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 < 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 tag, 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 the attribute value itself. The single-quote character ('), when used to quote an attribute value, must also be escaped as ' or ' (should NOT be escaped as ' except in XHTML documents) when it appears within 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
Character encoding
A character encoding system consists of a code that pairs a sequence of character from a given character set with something else, such as a sequence of natural numbers, octet or electrical pulses, in order to facilitate the transmission of data through telecommunication networks and/or Computer data storage of Character in compute... to be represented within the element and attribute content. For example, the acute-accented e (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 and are supported in all character encodings, whereas the literal é is not.
A data type in programming languages is an attribute of a data which tells the computer something about the kind of data it is. This involves setting constraints on the datum, such as what values it can take and what operations may be performed upon it.... s 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.
A Document Type Declaration, or DOCTYPE, is an instruction that associates a particular SGML or XML document with a Document Type Definition .... (informally, a “doctype”). In browsers, the function of the doctype is selecting the rendering mode—particularly to avoid the quirks mode
Quirks mode
Quirks mode refers to a technique used by some web browsers for the sake of maintaining backward compatibility with web pages designed for older browsers, instead of strictly complying with World Wide Web Consortium and Internet Engineering Task Force standards in standards mode.... .
Document Type Definition is one of several SGML and XML schema languages, and is also the term used to describe a document or portion thereof that is authored in the DTD language.... (DTD) with SGML tools. The DTD to which the DOCTYPE refers contains machine-readable grammar specifying the permitted and prohibited content for a document conforming to such a DTD. Browsers do not read the DTD, however. HTML5 validation is not DTD-based, so in HTML5 the doctype does not refer to a DTD.
An example of an HTML 4 doctype:
This declaration references the Strict DTD of HTML 4.01, which does not have presentational elements like , 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 standards layout mode for CSS
Cascading Style Sheets
Cascading Style Sheets is a stylesheet language used to describe the presentation of a document written in a markup language. Its most common application is to style web pages written in HTML and XHTML, but the language can be applied to any kind of XML document, including Scalable Vector Graphics and XUL.... as opposed to quirks mode
Quirks mode
Quirks mode refers to a technique used by some web browsers for the sake of maintaining backward compatibility with web pages designed for older browsers, instead of strictly complying with World Wide Web Consortium and Internet Engineering Task Force standards in standards 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.
Semantic HTML
There is no official specification called "Semantic HTML". Semantic HTML refers to a practice to create documents with HTML that contain only the author's intended meaning, without any reference to how this meaning is presented. It is part of the idea of separation of presentation and content
Separation of presentation and content
Separation of presentation and content is common idiom, a design philosophy, and a methodology applied in the context of various Publishing disciplines, including information retrieval, template processor, web design, web development, word processing, desktop publishing, and model-driven development.... . For example, the emphasis element (<em>) and the italics element (<i>) are functionally identical at default, but have two different meanings. The meaning behind the markup is important in semantic HTML.
CSS is typically used to create presentational effects for semantic HTML. With CSS, a designer can create the content with the appropriate, semantic markup and then use CSS to alter the appearance of their markup. The idea is that strictly presentational elements (such as italics or bold lettering) should not be used in the code and that any use of presentational elements should have some meaning attached to it, such as a citation.
The benefit of semantic HTML is that presentation of the text will be consistently applied, so long as the proper markup is consistently applied. Moreover, it allows for easy change of presentation, by simply editing the style sheets as well as being able to transfer the text from one site to another.
The main disadvantage is that HTML does not contain enough markup tags to describe every single conceivable description or meaning. As such, people will typically use the division (<div>) tag along with a set of pre-defined classes or IDs to properly mark up text for their intended meaning. If the designer has a glut of sections or meanings that don't fit well with HTML's markup, they may be forced to use a lot of division (<div>) tags, which could easily obfuscate the code.
Delivery of HTML
HTML documents can be delivered by the same means as any other computer file; however, they are most often delivered either by HTTP from a Web server or by e-mail.
The World Wide Web is a very large set of interlinked hypertext documents accessed via the Internet. With a Web browser, one can view Web pages that may contain writing, s, videos, and other multimedia and navigate between them using hyperlinks.... is composed primarily of HTML documents transmitted from Web server
Web server
The term web server can mean one of two things:# A computer program that is responsible for accepting Hypertext Transfer Protocol requests from clients , and Server them HTTP responses along with optional data contents, which usually are web pages such as Hypertext Markup Language documents and linked objects .... s to Web browsers using the Hypertext Transfer Protocol
Hypertext Transfer Protocol
Hypertext Transfer Protocol is an application-level protocol for distributed, collaborative, hypermedia information systems. Its use for retrieving inter-linked resources led to the establishment of the World Wide Web.... (HTTP). However, HTTP is used to serve images, sound, and other content in addition to HTML. To allow the Web browser to know how to handle each document it receives, other information is transmitted along with the document. This metadata
Metadata
Metadata is "data about other data", of any sort in any media. An item of metadata may describe an individual datum, or content item, or a collection of data including multiple content items and hierarchical levels, for example a database schema.... usually includes the MIME
MIME
Multipurpose Internet Mail Extensions is an Internet standard that extends the format of electronic mail to support:* Text in character sets other than ASCII... type (e.g. text/html or application/xhtml+xml) and the character encoding (see Character encodings in HTML
Character encodings in HTML
HTML has been in use since 1991, but HTML 4.0 was the first standardized version where international character s were given reasonably complete treatment.... ).
In modern browsers, the MIME type that is sent with the HTML document may affect how the document is initially interpreted. A document sent with the XHTML MIME type is expected to be well-formed XML, and syntax errors may cause the browser to fail to render it. The same document sent with the HTML MIME type might be displayed successfully, since some browsers are more lenient with HTML.
The W3C recommendations state that XHTML 1.0 documents that follow guidelines set forth in the recommendation's Appendix C may be labeled with either MIME Type. The current XHTML 1.1 Working Draft also states that XHTML 1.1 documents should be labeled with either MIME type.
Electronic mail, often abbreviated as e-mail, email, E-Mail, or eMail, is any method of creating, transmitting, or storing primarily text-based human communications with digital communications systems.... clients allow the use of a subset of HTML (often ill-defined) to provide formatting and semantic
Semantic Web
The Semantic Web is an evolving extension of the World Wide Web in which the semantics of information and services on the web is defined, making it possible for the web to understand and satisfy the requests of people and machines to use the web content.... markup not available with plain text
Plain text
In computing, plain text is a term used for an ordinary "unformatted" sequential file readable as textual material without much processing.The Character encoding has traditionally been either ASCII, one of its many derivatives such as ISO/IEC 646 etc., or sometimes EBCDIC.... . This may include typographic information like coloured headings, emphasized and quoted text, inline images and diagrams. Many such clients include both a GUI
Gui
Gui or guee is a generic term to refer to grillinged dishes in Korean cuisine. These most commonly have meat or fish as their primary ingredient, but may in some cases also comprise grilled vegetables or other vegetarian ingredients.... editor for composing HTML e-mail messages and a rendering engine for displaying them. Use of HTML in e-mail is controversial because of compatibility issues, because it can help disguise phishing
Phishing
In the field of computer security, phishing is the criminally fraudulent process of attempting to acquire sensitive information such as usernames, passwords and credit card details by masquerading as a trustworthy entity in an electronic communication.... attacks, because it can confuse spam
E-mail spam
E-mail spam, also known as junk e-mail, is a subset of spam that involves nearly identical messages sent to numerous recipients by e-mail.... filters and because the message size is larger than plain text.
A filename extension is a substring to the filename of a computer file applied to indicate the encoding convention of its contents.In some operating systems it is optional, while in some others it is a requirement.... for files
Computer file
A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable computer storage.... containing HTML is .html. A common abbreviation of this is .htm, which originated because some early operating systems and file systems, such as DOS
DOS
DOS, short for "Disk Operating System", is a shorthand term for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions Windows 95, Windows 98, and Windows Me.... and FAT
File Allocation Table
File Allocation Table or FAT is a computer file system architecture now widely used on most computer systems and most memory cards, such as those used with digital cameras.... , limited file extensions to three letters. See 8.3 filename.
Current flavors of HTML
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 for building both meaningful and well-presented documents. To return HTML to its role as a semantic language, the W3C
World Wide Web Consortium
The World Wide Web Consortium is the main international standards organization for the World Wide Web . It is arranged as a consortium where member organizations maintain full-time staff for the purpose of working together in the development of standards for the World Wide Web.... has developed style languages such as CSS
Cascading Style Sheets
Cascading Style Sheets is a stylesheet language used to describe the presentation of a document written in a markup language. Its most common application is to style web pages written in HTML and XHTML, but the language can be applied to any kind of XML document, including Scalable Vector Graphics and XUL.... and XSL
Extensible Stylesheet Language
In computing, the Extensible Stylesheet Language , a family of transformation languages, allows one to describe how to format or transform files encoded in the XML standard.... to shoulder the burden of presentation. In conjunction, the HTML specification has slowly reined in the presentational elements.
There are two axes differentiating various flavors of HTML as currently specified: SGML-based HTML versus XML-based HTML (referred to as XHTML) on one axis, and strict versus transitional (loose) versus frameset on the other axis.
SGML-based versus XML-based HTML
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; 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, they are sometimes documented in parallel. In such circumstances, some authors conflate the two names as (X)HTML or X(HTML).
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—are 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 shorthand, which is not used in the SGML declaration for HTML 4.01, 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 that adheres to Appendix C (see below) into a valid HTML 4.01 document. To make this translation requires the following steps:
The language for an element should be specified with a lang attribute rather than the XHTML xml:lang attribute. XHTML uses XML's built in language-defining functionality attribute.
Remove the XML namespace (xmlns=URI). HTML has no facilities for namespaces.
Change the document type declaration from XHTML 1.0 to HTML 4.01. (see DTD section for further explanation).
If present, remove the XML declaration. (Typically this is: ).
Ensure that the document’s MIME type is set to text/html. For both HTML and XHTML, this comes from the HTTP Content-Type header sent by the server.
Change the XML empty-element syntax to an HTML style empty element (<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 tags within an HTML document rather than remembering which tags 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 ). The following steps can be applied to XHTML 1.0 documents only:
Include both xml:lang and lang attributes on any elements assigning language.
Use the empty-element syntax only for elements specified as empty in HTML.
Include an extra space in empty-element tags: for example <br /> instead of <br/>.
Include explicit close tags for elements that permit content but are left empty (for example, <div></div>, not <div />).
Omit the XML declaration.
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 that are XHTML 1.0 and have been made compatible in this way, the W3C permits them to be 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.
Transitional versus Strict
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 are the same in HTML 4 and XHTML 1.0) are:
A looser content model
Inline elements and plain text (#PCDATA) are allowed directly in: body, blockquote, form, noscript and noframes
Presentation related elements
underline (u)
strike-through (s)
center
font
basefont
Presentation related attributes
background and bgcolor attributes for body element.
align attribute on div, form, paragraph (p), and heading (h1...h6) elements
align, noshade, size, and width attributes on hr element
align, border, vspace, and hspace attributes on img and object elements
align attribute on legend and caption elements
align and bgcolor on table element
nowrap, bgcolor, width, height on td and th elements
bgcolor attribute on tr element
clear attribute on br element
compact attribute on dl, dir and menu elements
type, compact, and start attributes on ol and ul elements
type and value attributes on li element
width attribute on pre element
Additional elements in Transitional specification
menu 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)
The language attribute on script element (presumably redundant with type attribute, though this is maintained for legacy reasons).
Frame related entities
frameset element (used in place of body for frameset DTD)
frame element
iframe
noframes
target attribute on anchor, client-side image-map (imagemap), link, form, and base elements
Frameset versus transitional
In addition to the above transitional differences, the frameset specifications (whether XHTML 1.0 or HTML 4.01) specifies a different content model:
Summary of flavours
As this list demonstrates, the loose flavours 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
MathML
Mathematical Markup Language is an application of XML for describing mathematics notations and capturing both its structure and content. It aims at integrating mathematical formulae into World Wide Web documents.... (a presentational and semantic math language based on XML) and XForms
XForms
XForms is an XML format for the specification of a data processing model for XML data and user interface for the XML data, such as form . XForms was designed to be the next generation of HTML / XHTML forms, but is generic enough that it can also be used in a standalone manner or with presentation languages other than XHTML to describe a user... —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.
Hypertext features not in HTML
HTML lacks some of the features found in earlier hypertext systems, such as typed link
Typed link
A typed link in a hypertext system is a link to another document or part of a document that includes information about the character of the link.... s, source tracking
Source tracking
Source tracking pertains to the ability of some hypertext systems to rigorously track the exact source of every document or partial document included in the system; that is, they remember who entered the information, when it was entered, when it was updated and by whom, and so on.... , fat link
Fat link
A fat link is a hyperlink which leads to multiple endpoints: the link is a multivalued function.The hyperlinks that are attached to the same design object can be grouped into a fat link for representational purposes, and the activation of a fat link gives a menu of the links contained in it , from which individual links can then be activate... s, and more. 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, wiki
Wiki
A wiki is a page or collection of Web pages designed to enable anyone who accesses it to contribute or modify content , using a simplified markup language.... s and content management system
Content management system
A content management system is a computer application used to create, edit, manage, search and publish various kinds of Content . CMSs are frequently used for storing, controlling, versioning, and publishing industry-specific documentation such as news articles, operators' manuals, technical manuals, sales guides, and marketing brochures.... s allow surfers to edit the Web pages they visit.
See also
External links
HTML Reference
HTML Tutorials
HTML Markup Validators
for Windows
Standard HTML specifications
Refer to the HTML version history section
Other specifications
A specification generally referred to as "HTML 5". The Web Hypertext Application Technology working group are an independent initiative who cooperate with the W3C.
