Editing Markup language

{{Short description|Modern system for annotating a document}}
[[File:RecipeML egg nog.svg|thumb|Example of [[RecipeML]], a simple markup language based on XML for creating recipes. The markup can be converted programmatically for display into, for example, [[HTML]], [[Portable Document Format|PDF]] or [[Rich Text Format]].|alt=A screenshot of an XML file.]]
A '''markup''' '''language''' is a [[Encoding|text-encoding system]] which specifies the structure and formatting of a document and potentially the relationships among its parts.<ref>{{Cite news |title=markup language {{!}} Definition, Examples, & Facts |language=en |work=Encyclopedia Britannica |url=https://www.britannica.com/technology/markup-language |access-date=2022-08-17 |archive-date=2020-10-26 |archive-url=https://web.archive.org/web/20201026080719/https://www.britannica.com/technology/markup-language |url-status=live }}</ref> Markup can control the display of a document or enrich its content to facilitate automated processing.

A markup language is a set of rules governing what markup information may be included in a document and how it is combined with the content of the document in a way to facilitate use by humans and computer programs. The idea and [[terminology]] evolved from the "marking up" of paper [[manuscript]]s (e.g., with revision instructions by editors), traditionally written with a red pen or [[blue pencil (editing)|blue pencil]] on authors' manuscripts.<ref>{{cite book|author1-last=Siechert
|author1-first=Carl |author2-last=Bott |author2-first=Ed|title=Microsoft Office Inside Out: 2013 Edition |url=https://books.google.com/books?id=TbhCAwAAQBAJ|year=2013 |publisher=Pearson Education |isbn=978-0735669062 |page=305 |quote=Some reviewers prefer going old school by using a red pen on printed output}}</ref>

Older markup languages, which typically focus on typography and presentation, include [[Troff]], [[TeX]], and [[LaTeX]].
[[Scribe (markup language)|Scribe]] and most modern markup languages, such as [[Extensible Markup Language|XML]], identify document components (for example headings, paragraphs, and tables), with the expectation that technology, such as [[Style sheet (web development)|stylesheets]], will be used to apply formatting or other processing.{{Citation needed|date=February 2024}}

Some markup languages, such as the widely used [[HTML]], have pre-defined [[presentation semantics]], meaning that their specifications prescribe some aspects of how to present the [[structured data]] on particular media. HTML, like [[DocBook]], [[Open eBook]], [[JATS]], and many others, is based on the markup metalanguages [[Standard Generalized Markup Language|SGML]] and [[XML]]. That is, SGML and XML allow designers to specify particular [[XML schema|schema]]s, which determine which elements, attributes, and other features are permitted, and where.<ref>{{cite web |author=<!-- not stated --> |date=<!-- not stated --> |url=https://sgmljs.net/docs/markdown-typography-examples.html# |website=smljs.net |title=SGML Markdown Typography Documentation |access-date=2025-01-02}}</ref>

A key characteristic of most markup languages is that they allow intermingling markup with document content such as text and pictures. For example, if a few words in a [[Sentence (linguistics)|sentence]] need to be emphasized, or identified as a proper name, defined term, or another special item, the markup may be inserted between the characters of the sentence. 

==Etymology<span class="anchor" id="Etymology and origin"></span>==

The noun ''markup'' is derived from the traditional publishing practice called ''"marking up"'' a [[manuscript]], which involves adding handwritten annotations in the form of conventional symbolic [[Printing|printer]]'s instructions — in the margins and the text of a paper or a printed manuscript. 

For centuries, this task was done primarily by skilled typographers known as "markup men"<ref>Allan Woods, ''Modern Newspaper Production'' (New York: Harper & Row, 1963), 85; Stewart Harral, ''Profitable Public Relations for Newspapers'' (Ann Arbor: J.W. Edwards, 1957), 76; and ''Chiarella v. United States'', {{ussc|445|222|1980}}.</ref> or "markers"<ref>'' From the Notebooks of H.J.H & D.H.An on Composition'', Kingsport Press Inc., undated (the 1960s).</ref> who marked up text to indicate what [[typeface]], style, and size should be applied to each part, and then passed the manuscript to others for [[typesetting]] by hand or machine. 

The markup was also commonly applied by editors, [[proofreader]]s, publishers, and graphic designers, and indeed by document authors, all of whom might also mark other things, such as corrections, changes, etc.

==Types of markup language==
There are three main general categories of electronic markup, articulated in Coombs, Renear, and [[Steven Derose|DeRose]] (1987),<ref>{{cite journal |date=November 1987 |title=Markup systems and the future of scholarly text processing |journal=[[Communications of the ACM]] |volume=30 |issue=11 |pages=933–947 |doi=10.1145/32206.32209 |url=http://xml.coverpages.org/coombs.html |first1=James H. |last1=Coombs |first2=Allen H. |last2=Renear |first3=Steven J. |last3=DeRose |citeseerx=10.1.1.515.5618 |s2cid=59941802 |access-date=2005-04-19 |archive-date=2019-05-12 |archive-url=https://web.archive.org/web/20190512040939/http://xml.coverpages.org/coombs.html |url-status=live }}</ref> and [[Tim Bray|Bray]] (2003).<ref>{{cite web |last=Bray |first=Tim |author-link=Tim Bray |url=https://www.tbray.org/ongoing/When/200x/2003/04/09/SemanticMarkup#p-1 |title=On Semantics and Markup, Taxonomy of Markup |website=www.tbray.org |date=9 April 2003 |access-date=2021-08-16 |archive-date=2021-02-27 |archive-url=https://web.archive.org/web/20210227074013/https://www.tbray.org/ongoing/When/200x/2003/04/09/SemanticMarkup#p-1 |url-status=live }}</ref>

=== Presentational markup ===
:The kind of markup used by traditional [[Word processor (electronic device)|word-processing]] systems: [[Binary code|binary codes]] embedded within document text that produce the [[WYSIWYG]] ("'''what you see is what you get'''") effect. Such markup is usually hidden from human users, even authors and editors. Properly speaking, such systems use procedural and/or descriptive markup underneath but convert it to "present" to the user as geometric arrangements of type.{{Citation needed|date=February 2024}}

=== Procedural markup ===
:Markup is embedded in text which provides [[Opcode|instructions]] for [[Programming language|programs]] to process the text. Well-known examples include [[troff]], [[TeX]], and [[Markdown]]. It is assumed that software processes the text sequentially from beginning to end, following the instructions as encountered. Such text is often edited with the markup visible and directly manipulated by the author. Popular procedural markup systems usually include [[Process (computing)|programming constructs]], especially [[Macro (computer science)|macros]], allowing complex sets of instructions to be invoked by a simple name (and perhaps a few parameters). This is much faster, less error-prone, and more maintenance-friendly than re-stating the same or similar instructions in many places.

=== Descriptive markup ===
: Markup is specifically used to label parts of the document for what they are, rather than how they should be processed. Well-known systems that provide many such labels include [[LaTeX]], [[HTML]], and [[XML]]. The objective is to [[Separation of content and presentation|decouple the structure]] of the document from any particular treatment or rendition of it. Such markup is often described as "[[Semantic HTML|semantic]]". An example of a descriptive markup would be HTML's <code>&lt;cite></code> tag, which is used to label a citation. Descriptive markup — sometimes called ''logical markup'' or ''conceptual markup'' — encourages authors to write in a way that describes the material conceptually, rather than visually.<ref>Michael Downes.[https://www.ams.org/notices/200211/comm-downes.pdf "TEX and LATEX 2e"] {{Webarchive|url=https://web.archive.org/web/20210524182136/http://www.ams.org/notices/200211/comm-downes.pdf |date=2021-05-24 }}</ref>

There is a considerable blurring of the lines between the types of markup. In modern word-processing systems, presentational markup is often saved in descriptive-markup-oriented systems such as [[XML]], and then processed procedurally by [[Implementation|implementations]]. The programming in procedural-markup systems, such as [[TeX]], may be used to create higher-level markup systems that are more descriptive in nature, such as [[LaTeX]].

In recent years, several markup languages have been developed with ease of use as a key goal, and without input from standards organizations, aimed at allowing authors to create formatted text via [[Web browser|web browsers]], for example in [[wiki]]s and in [[Internet forum|web forums]]. These are sometimes called [[lightweight markup language]]s. [[Markdown]], [[BBCode]], and the [[Wikitext|markup language used by Wikipedia]] are examples of such languages.

==History of markup languages<span class="anchor" id="History"></span>==
===GenCode===
The first well-known public presentation of markup languages in computer text processing was made by [[William W. Tunnicliffe]] at a conference in 1967, although he preferred to call it ''generic coding.'' It can be seen as a response to the emergence of programs such as [[RUNOFF]] that each used their own control notations, often specific to the target typesetting device. In the 1970s, Tunnicliffe led the development of a standard called GenCode for the publishing industry and later was the first chairman of the [[International Organization for Standardization]] committee that created [[SGML]], the first standard descriptive markup language. [[Book design|Book designer]] Stanley Rice published speculation along similar lines in 1970.<ref>Rice, Stanley. “Editorial Text Structures (with some relations to information structures and format controls in computerized composition).” American National Standards Institute, March 17, 1970.</ref>

[[Brian Reid (computer scientist)|Brian Reid]], in his 1980 dissertation at [[Carnegie Mellon University]], developed the theory and a working implementation of descriptive markup in actual use. However, [[IBM]] researcher [[Charles Goldfarb]] is more commonly seen today as the "father" of markup languages. Goldfarb hit upon the basic idea while working on a primitive document management system intended for law firms in 1969, and helped invent [[IBM Generalized Markup Language|IBM GML]] later that same year. GML was first publicly disclosed in 1973.

In 1975, Goldfarb moved from [[Cambridge, Massachusetts]] to [[Silicon Valley]] and became a product planner at the [[IBM Almaden Research Center]]. There, he convinced IBM's executives to deploy GML commercially in 1978 as part of IBM's Document Composition Facility product, and it was widely used in business within a few years.

SGML, which was based on both GML and GenCode, was an [[International Organization for Standardization|ISO]] project worked on by Goldfarb beginning in 1974.<ref>{{cite web|url=http://www.drdobbs.com/blog/archives/2009/08/beyond_html_an.html|title=2009 interview with SGML creator Charles F. Goldfarb|publisher=[[Dr. Dobb's Journal]]|access-date=2010-07-18}}{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Goldfarb eventually became chair of the SGML committee. SGML was first released by ISO as the ISO 8879 standard in October 1986.

===troff and nroff===
{{Main|troff}}
Some early examples of computer markup languages available outside the publishing industry can be found in typesetting tools on [[Unix]] systems such as [[troff]] and [[nroff]]. In these systems, formatting commands were inserted into the document text so that typesetting software could format the text according to the editor's specifications. It was a [[trial and error]] iterative process to get a document printed correctly.<ref>Daniel Gilly. [http://web.deu.edu.tr/doc/oreily/unix/unixnut/ch12_01.htm ''Unix in a nutshell: Chapter 12. Groff and Troff''] {{Webarchive|url=https://web.archive.org/web/20160105180006/http://web.deu.edu.tr/doc/oreily/unix/unixnut/ch12_01.htm |date=2016-01-05 }}. O'Reilly Books, 1992. {{ISBN|1-56592-001-5}}</ref> Availability of [[WYSIWYG]] ("what you see is what you get") publishing software supplanted much use of these languages among casual users, though serious publishing work still uses markup to specify the non-visual structure of texts, and WYSIWYG editors now usually save documents in a markup-language-based format.

===TeX===
{{Main|TeX}}
Another major publishing standard is [[TeX]], created and refined by [[Donald Knuth]] in the 1970s and '80s. [[TeX]] concentrated on the detailed layout of text and font descriptions to typeset mathematical books. This required Knuth to spend considerable time investigating the art of [[typesetting]]. TeX is mainly used in [[academia]], where it is a [[De facto standard|''de facto'' standard]] in many scientific disciplines. A TeX macro package known as [[LaTeX]] provides a descriptive markup system on top of TeX, and is widely used both among the scientific community and the publishing industry.

===Scribe, GML, and SGML===
{{Main|Scribe (markup language)|IBM Generalized Markup Language|Standard Generalized Markup Language}}
The first language to make a clean distinction between structure and presentation was [[Scribe (markup language)|Scribe]], developed by [[Brian Reid (computer scientist)|Brian Reid]] and described in his doctoral thesis in 1980.<ref>Reid, Brian. "Scribe: A Document Specification Language and its Compiler". Ph.D. thesis, Carnegie-Mellon University, Pittsburgh PA. Also available as Technical Report CMU-CS-81-100.</ref> Scribe was revolutionary in a number of ways, introducing the idea of styles separated from the marked-up document, and a [[grammar]] that controlled the usage of descriptive elements. Scribe influenced the development of [[IBM Generalized Markup Language|Generalized Markup Language]] (later SGML),<ref>{{Cite web|url=http://xml.coverpages.org/mt98-papers.html#reid|title=20 Years of Abstract Markup - Any Progress?|last=Reid|first=Brian|author-link=Brian Reid (computer scientist)|website=xml.coverpages.org|access-date=2021-08-16|archive-date=2019-05-01|archive-url=https://web.archive.org/web/20190501150514/http://xml.coverpages.org/mt98-papers.html#reid|url-status=live}}</ref> and is a direct ancestor to [[HTML]] and [[LaTeX]].<ref>HTML is a particular instance of SGML, whereas LaTeX is designed with the separation-between-content-and-design philosophy of Scribe in mind.</ref>

In the early 1980s, the idea that markup should focus on the structural aspects of a document and leave the visual presentation of that structure to the interpreter led to the creation of [[Standard Generalized Markup Language|SGML]]. The language was developed by a committee chaired by Goldfarb. It incorporated ideas from many different sources, including Tunnicliffe's project, GenCode. Sharon Adler, Anders Berglund, and James A. Marke were also key members of the SGML committee.

SGML specified a syntax for including the markup in documents, as well as one for separately describing ''what'' tags were allowed, and ''where'' (the Document Type Definition ([[Document Type Definition|DTD]]), later known as a [[XML schema|schema]]). This allowed authors to create and use any markup they wished, selecting tags that made the most sense to them and were named in their own natural languages, while also allowing automated verification. Thus, SGML is properly a [[metalanguage]], and many particular markup languages are derived from it. From the late '80s onward, most substantial new markup languages have been based on the SGML system, including for example [[Text Encoding Initiative|TEI]] and [[DocBook]]. SGML was promulgated as an International Standard by [[International Organization for Standardization]], ISO 8879, in 1986.<ref>{{Cite web|url=https://www.iso.org/standard/16387.html|title=ISO 8879:1986|website=ISO|access-date=2021-08-15|archive-date=2021-08-17|archive-url=https://web.archive.org/web/20210817024719/https://www.iso.org/standard/16387.html|url-status=live}}</ref>

SGML found wide acceptance and use in fields with very large-scale documentation requirements. However, many found it cumbersome and difficult to learn — a side effect of its design attempting to do too much and being too flexible. For example, SGML made end tags (or start-tags, or even both) optional in certain contexts, because its developers thought markup would be done manually by overworked support staff who would appreciate saving keystrokes{{Citation needed|date=August 2008}}.

====HTML====
{{Main|HTML}}
In 1989, computer scientist [[Tim Berners-Lee|Sir Tim Berners-Lee]] wrote a memo proposing an [[Internet]]-based [[hypertext]] system,<ref>Tim Berners-Lee, "[https://www.w3.org/History/1989/proposal.html Information Management: A Proposal]". CERN (March 1989, May 1990). W3C. {{Webarchive|url=https://web.archive.org/web/20100401051011/https://www.w3.org/History/1989/proposal.html |date=2010-04-01 }}</ref> then specified HTML and wrote the browser and server software in the last part of 1990. The first publicly available description of HTML was a document called "HTML Tags", first mentioned on the Internet by Berners-Lee in late 1991.<ref name="tagshtml">{{cite web |url=https://www.w3.org/History/19921103-hypertext/hypertext/WWW/MarkUp/Tags.html |title=Tags used in HTML |publisher=World Wide Web Consortium |date=November 3, 1992 |access-date=2021-08-16 |archive-date=2010-01-31 |archive-url=https://web.archive.org/web/20100131184344/http://www.w3.org/History/19921103-hypertext/hypertext/WWW/MarkUp/Tags.html |url-status=live }}</ref><ref>{{cite web|url=https://lists.w3.org/Archives/Public/www-talk/1991SepOct/0003.html|title=First mention of HTML Tags on the www-talk mailing list|publisher=World Wide Web Consortium|date=October 29, 1991|access-date=August 16, 2021|archive-date=August 8, 2021|archive-url=https://web.archive.org/web/20210808223716/https://lists.w3.org/Archives/Public/www-talk/1991SepOct/0003.html|url-status=live}}</ref> It describes 18 elements comprising the initial, relatively simple design of HTML. Except for the hyperlink tag, these were strongly influenced by [[SGMLguid]], an in-house [[SGML]]-based documentation format at [[CERN]], and very similar to the sample schema in the SGML standard. Eleven of these elements still exist in HTML 4.<ref>{{cite web|url=https://www.w3.org/TR/1999/REC-html401-19991224/index/elements|title=Index of elements in HTML 4|publisher=World Wide Web Consortium|date=December 24, 1999|access-date=2021-08-16|archive-date=2007-05-05|archive-url=https://web.archive.org/web/20070505172415/https://www.w3.org/TR/1999/REC-html401-19991224/index/elements|url-status=live}}</ref>

Berners-Lee considered HTML an SGML application. The [[Internet Engineering Task Force]] (IETF) formally defined it as such with the mid-1993 publication of the first proposal for an HTML specification: [https://www.w3.org/MarkUp/draft-ietf-iiir-html-01.txt "Hypertext Markup Language (HTML)" Internet-Draft] {{Webarchive|url=https://web.archive.org/web/20170103041713/https://www.w3.org/MarkUp/draft-ietf-iiir-html-01.txt |date=2017-01-03 }} by Berners-Lee and [[Dan Connolly (computer scientist)|Dan Connolly]], which included an SGML [[Document Type Definition]] to define the grammar.<ref>{{cite web|url=https://lists.w3.org/Archives/Public/www-talk/1991NovDec/0020.html|title=Re: SGML/HTML docs, X Browser (archived www-talk mailing list post)|author=Tim Berners-Lee|author-link=Tim Berners-Lee|date=December 9, 1991|quote=SGML is very general. HTML is a specific application of the SGML basic syntax applied to hypertext documents with a simple structure.|access-date=August 16, 2021|archive-date=July 3, 2021|archive-url=https://web.archive.org/web/20210703084047/https://lists.w3.org/Archives/Public/www-talk/1991NovDec/0020.html|url-status=live}}</ref> Many of the HTML text elements are found in the 1988 ISO technical report TR 9537 ''Techniques for using SGML'', which in turn covers the features of early text formatting languages such as that used by the [[TYPSET and RUNOFF|RUNOFF command]] developed in the early 1960s for the [[Compatible Time-Sharing System|CTSS]] (Compatible Time-Sharing System) operating system. These formatting commands were derived from those used by typesetters to manually format documents. [[Steven DeRose]]<ref>DeRose, Steven J. "The SGML FAQ Book". Boston: Kluwer Academic Publishers, 1997. {{ISBN|0-7923-9943-9}}</ref> argues that HTML's use of descriptive markup (and the influence of SGML in particular) was a major factor in the success of the Web, because of the flexibility and extensibility that it enabled. HTML became the main markup language for creating web pages and other information that can be displayed in a web browser and is likely the most used markup language in the world today.

===XML===
{{Main|XML}}

XML (Extensible Markup Language) is a meta markup language that is very widely used. XML was developed by the [[World Wide Web Consortium]] in a committee created and chaired by [[Jon Bosak]]. The main purpose of XML was to simplify SGML by focusing on a particular problem — documents on the Internet.<ref>{{cite web |url=https://www.w3.org/TR/xml11/ |date=16 August 2006 |title=Extensible Markup Language (XML) 1.1 (Second Edition) |publisher=W3C |access-date=2021-08-16 |archive-date=2021-08-11 |archive-url=https://web.archive.org/web/20210811223058/https://www.w3.org/TR/xml11/ |url-status=live }}</ref> XML remains a metalanguage like SGML, allowing users to create any tags needed (hence "extensible") and then describing those tags and their permitted uses.

XML adoption was helped because every XML document can be written in such a way that it is also an SGML document, and existing SGML users and software could switch to XML fairly easily. However, XML eliminated many of the more complex features of SGML to simplify implementation environments such as documents and publications. It appeared to strike a happy medium between simplicity and flexibility, as well as supporting very robust schema definition and validation tools, and was rapidly adopted for many other uses. XML is now widely used for communicating [[database transaction|data]] between applications, for serializing program data, for hardware communications protocols, vector graphics, and many other uses as well as documents.

====XHTML====
{{Main|XHTML}}
From January 2000 until HTML 5 was released, all [[W3C Recommendation]]s for HTML have been based on XML, using the abbreviation [[XHTML]] ('''Ex'''tensible '''H'''yper'''T'''ext '''M'''arkup '''L'''anguage). The language specification requires that XHTML Web documents be ''well-formed'' XML documents. This allows for more rigorous and robust documents, by avoiding many syntax errors which historically led to incompatible browser behaviors, while still using document components that are familiar with HTML.

One of the most noticeable differences between HTML and XHTML is the rule that ''all tags must be closed'': empty HTML tags such as <code><nowiki><br></nowiki></code> must either be ''closed'' with a regular end-tag, or replaced by a special form: {{nowrap|<code><nowiki><br /></nowiki></code>}} (the space before the '<code><nowiki>/</nowiki></code>' on the end tag is optional, but frequently used because it enables some pre-XML Web browsers, and SGML parsers, to accept the tag). Another difference is that all [[HTML#Attributes|attribute]] values in tags must be quoted. Both these differences are commonly criticized as verbose but also praised because they make it far easier to detect, localize, and repair errors. Finally, all tag and attribute names within the XHTML namespace must be lowercase to be valid. HTML, on the other hand, was case-insensitive.

====Other XML-based applications====
Many XML-based applications now exist, including the [[Resource Description Framework]] as [[RDF/XML]], [[XForms]], [[DocBook]], [[Simple Object Access Protocol|SOAP]], and the [[Web Ontology Language]] (OWL). For a partial list of these, see [[List of XML markup languages]].

==Features of markup languages<span class="anchor" id="Features"></span>==
A common feature of many markup languages is that they intermix the text of a document with markup instructions in the same data stream or file. This is not necessary; it is possible to isolate markup from text content, using pointers, offsets, IDs, or other methods to coordinate the two. Such "standoff markup" is typical for the internal representations that programs use to work with marked-up documents. However, embedded or "inline" markup is much more common elsewhere. Here, for example, is a small section of text marked up in HTML:

<syntaxhighlight lang="html" line="1">
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>My test page</title>
  </head>
  <body>
    <h1>Mozilla is cool</h1>
    <img src="images/firefox-icon.png" alt="The Firefox logo: a flaming fox surrounding the Earth.">

    <p>At Mozilla, we’re a global community of</p>

    <ul> <!-- changed to list in the tutorial -->
      <li>technologists</li>
      <li>thinkers</li>
      <li>builders</li>
    </ul>

    <p>working together to keep the Internet alive and accessible, so people worldwide can be informed contributors and creators of the Web. We believe this act of human collaboration across an open platform is essential to individual growth and our collective future.</p>

    <p>Read the <a href="https://www.mozilla.org/en-US/about/manifesto/">Mozilla Manifesto</a> to learn even more about the values and principles that guide the pursuit of our mission.</p>
  </body>
</html>
</syntaxhighlight>

The codes enclosed in angle-brackets <code>&lt;like this&gt;</code> are markup instructions (known as tags), while the text between these instructions is the actual text of the document. The codes <code>h1</code>, <code>p</code>, and <code>em</code> are examples of ''semantic'' markup, in that they describe the intended purpose or the meaning of the text they include. Specifically, <code>h1</code> means "this is a first-level heading", <code>p</code> means "this is a paragraph", and <code>em</code> means "this is an emphasized word or phrase". A program interpreting such structural markup may apply its own rules or styles for presenting the various pieces of text, using different typefaces, boldness, font size, indentation, color, or other styles, as desired. For example, a tag such as "h1" (header level 1) might be presented in a large bold sans-serif typeface in an article, or it might be underscored in a monospaced (typewriter-style) document &ndash; or it might simply not change the presentation at all.

In contrast, the <code>i</code> tag in HTML 4 is an example of ''presentational'' markup, which is generally used to specify a particular characteristic of the text without specifying the reason for that appearance. In this case, the <code>i</code> element dictates the use of an italic typeface. However, in [[HTML 5]], this element has been repurposed with a more semantic usage: to denote <q cite="https://html.spec.whatwg.org/#the-i-element">a span of text in an alternate voice or mood, or otherwise offset from the normal prose in a manner indicating a different quality of text</q>. For example, it is appropriate to use the <code>i</code> element to indicate a taxonomic designation or a phrase in another language.<ref>{{cite web |last1=Hickson |first1=Ian |title=HTML Living Standard |url=https://html.spec.whatwg.org/#the-i-element |website=WHATWG — HTML |access-date=13 September 2020 |archive-date=8 March 2018 |archive-url=https://web.archive.org/web/20180308105412/https://html.spec.whatwg.org/#the-i-element |url-status=live }}</ref> The change was made to ease the transition from HTML 4 to HTML 5 as smoothly as possible so that deprecated uses of presentational elements would preserve the most likely intended semantics.

The [[Text Encoding Initiative]] (TEI) has published extensive guidelines<ref>{{cite web |url=https://www.tei-c.org/Guidelines/ |title=TEI Guidelines for Electronic Text Encoding and Interchange |publisher=Tei-c.org |access-date=2021-08-16 |archive-url=https://web.archive.org/web/20140703122400/https://www.tei-c.org/Guidelines/ |archive-date=2014-07-03}}</ref> for how to encode texts of interest in the humanities and social sciences, developed through years of international cooperative work. These guidelines are used by projects encoding historical documents, the works of particular scholars, periods, genres, and so on.

==Language==
While the idea of markup language originated with text documents, there is increasing use of markup languages in the presentation of other types of information, including [[playlist]]s, [[vector graphics]], [[web service]]s, [[web syndication|content syndication]], and [[user interface]]s. Most of these are XML applications because XML is a well-defined and extensible language.{{says who|date=July 2022}}

The use of XML has also led to the possibility of combining multiple markup languages into a single profile, like [[XHTML+SMIL]] and [[XHTML+MathML+SVG]].<ref>[https://www.w3.org/TR/2002/WD-XHTMLplusMathMLplusSVG-20020809/ An XHTML + MathML + SVG Profile] {{Webarchive|url=https://web.archive.org/web/20210719215421/https://www.w3.org/TR/2002/WD-XHTMLplusMathMLplusSVG-20020809/ |date=2021-07-19 }}. W3C. August 9, 2002. Retrieved 2021-08-16.</ref>

==See also==
* [[ADDML]]
* [[Comparison of document markup languages]]
* [[Curl (programming language)]]
* [[HTML]]
* [[LaTeX]]
* [[Lightweight markup language]]
* [[List of markup languages]]
* [[Markdown]]
* [[Programming language]]
* [[Modeling language]]
* [[Plain text]]
* [[Formatted text]]
* [[ReStructuredText]]
* [[SCRIPT (markup)]]
* [[Style sheet language]]
* [[Tag (markup)]]
*[[TYPSET and RUNOFF]]
* [[WYSIWYG]]
* [[XML]]

==References==
{{Reflist}}

==External links==
{{Spoken Wikipedia|Markup_language.ogg|date=2006-05-06}}
{{Wiktionary|markup language}}
{{Commons category|Markup languages}}
{{Markup languages}}
{{Computer language}}
{{Authority control}}

[[Category:Markup languages| ]]
[[Category:Formal languages]]
[[Category:American inventions]]