Markup & Markdown Madness!

A '''markup language''' is a system for [[annotation|annotating]] a [[document]] in a way that is [[Syntax (logic)|syntactically
distinguishable]] from the text.<ref>{{MerriamWebsterDictionary|markup language}}</ref> The idea and terminology evolved from the
"marking up" of paper manuscripts, i.e., the revision instructions by editors, traditionally written with a [[blue pencil (editing)|blue
pencil]] on authors' [[manuscript]]s.{{citation needed|date=July 2016}}

In [[digital media]] this "blue pencil instruction text" was replaced by [[HTML element|tags]], that is, instructions are expressed
directly by tags or "instruction text encapsulated by tags." Examples include typesetting instructions such as those found in [[troff]],
[[TeX]] and [[LaTeX]], or structural markers such as [[Extensible Markup Language|XML]] tags. Markup instructs the software that
displays the text to carry out appropriate actions, but is omitted from the version of the text that users see.

Some markup languages, such as the widely used [[HTML]], have pre-defined [[presentation semantics]]—meaning that their specification
prescribes how to present the [[structured data]]. Others, such as XML, do not have them and are general purpose.

[[Hypertext|HyperText]] Markup Language (HTML), one of the document formats of the [[World Wide Web]], is an instance of [[Standard
Generalized Markup Language|SGML]] (though, strictly, it does not comply with all the rules of SGML), and follows many of the markup
conventions used in the publishing industry in the communication of printed work between authors, editors, and printers.{{Citation
needed|date=March 2012}}
<!-- omitted example here as it is well covered below and is too specific -->

==Types==
There are three main general categories of electronic markup:<ref>{{cite journal|date=November 1987|title=Markup systems and the future
of scholarly text processing|journal=[[Communications of the ACM]]|publisher=[[Association for Computing
Machinery|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}}</ref><ref>{{cite web|last=Bray|first=Tim|authorlink=Tim
Bray|url=http://www.tbray.org/ongoing/When/200x/2003/04/09/SemanticMarkup#p-1|title=On Semantics and Markup, Taxonomy of
Markup|website=www.tbray.org/ongoing|date=9 April 2003|access-date=9 July 2015}}</ref>

;Presentational markup
:The kind of markup used by traditional word-processing systems: binary codes embedded within document text that produce the [[WYSIWYG]]
effect. Such markup is usually hidden from human users, even authors or editors.

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