Wikipedia:Manual of Style/Glossaries

On Wikipedia, a glossary is a special kind of list. Each glossary is an alphabetically arranged list of a subject's terms, with definitions. Each term is followed by one or more explanatory (encyclopedia-style) definitions. (For example, see Glossary of architecture).

In order to explain jargon for Wikipedia's broad audience, each of its glossaries contains a working vocabulary and definitions for important concepts for a given subject area. A glossary usually includes a field's technical terms, jargon, idioms, and metaphors.

Glossaries can be stand-alone list articles or embedded lists in sections of articles. Stand-alone glossaries are typically titled "Glossary of subject terms". A glossary within an article usually starts with the heading "Glossary".

Terminology
Every article on Wikipedia with a title in the form "Glossary of subject terms", or similar, is such a glossary, as are the glossary sections inside some articles. These are distinct from outlines, which are titled in the form "Outline of subject" and may also include definitions, but are organized as a hierarchy and use their own style of formatting not covered in this guideline. Glossary formatting, however, is not limited to only glossaries in the traditional sense. The underlying HTML description list markup is intended for groups of "terms and definitions, metadata topics and values, questions and answers, or any other groups of name–value data".

The following terms are used consistently throughout this guideline:

glossary: A list of individual entries, each consisting of a one-word or longer term with one or more definitions. Glossaries are subject to all of the same rules (e.g. Verifiability, and Neutral point of view) as other content on Wikipedia. list: A stand-alone list article or a list embedded in an article, consisting of entries in alphabetical order, and in one of the prescribed styles. The differences, for glossary-writing purposes, between stand-alone and embedded are covered below. entry: A discrete concept that can be unambiguously named with a term and described or otherwise addressed with a definition. term: A name or label for an entry, distinguishable from other entries. Usually there is only one term, though spelling variants and the like may sometimes result in multiple terms per entry. Like everything else on Wikipedia, the existence of the term must be verifiable. definition: Prose that addresses the term of the entry in an encyclopedically descriptive manner. While some definitions may be dictionary-like (e.g. for simple concepts, or entries for which insufficient reliable sources have been found to provide more detail yet), an entire glossary of such definitions is not appropriate on Wikipedia and is likely to be moved to Wiktionary. There are often two or more definitions per term. Definitions longer than a short paragraph may indicate a need for an article (or article section) about the topic of the term and a link to it from the glossary definition, in lieu of an in-depth definition in the glossary itself. style: The three glossary format styles to choose from are template-structured, bullet-style, and subheading-style. They are mutually exclusive. (By the way, this glossary you are reading right now in this Terminology section is template-structured.)

Glossary formatting styles
There are three styles to choose from when creating a glossary: template-structured, bullet-style, subheading-style, and (deprecated) semicolon-and-colon-style.

Template-structured
There is a special set of templates used for formatting glossary content. The templates are:
 * glossary – this template is used at the beginning of a block of glossary entries
 * term – this template sets the size and font style (bold) for each term
 * defn – this template provides the formatting for the term's definition prose.
 * glossary end – this template ends the block of glossary entries

Nearly all stand-alone, and most embedded, glossaries are good candidates for the template-structured format. Here's what the format looks like:

{|class="wikitable" style="width: 90%;"
 * style="width: 50%; vertical-align: top;"|
 * style="width: 50%; vertical-align: top;"|

A–M
Optional introductory text.

term A: Definition of term A term B: First definition of term B. Second definition of term B.


 * style="width: 50%; vertical-align: top; background-color: white;"|

Optional introductory text.

term A: Definition of term A term B: First definition of term B. Second definition of term B.


 * }

This formatting style produces cleaner and richer XHTML output from Wikipedia's MediaWiki software engine, and uses standard HTML elements specifically intended for glossary markup. It provides many benefits, and the syntax does not take long to learn. Glossaries using this style:
 * Are more accessible to those using screen readers, which is important for Wikipedia
 * Have directly linkable entries and other editorial benefits (with a simplicity tradeoff), such as code consistency
 * Enhance Wikipedia's application richness and usability, and make glossaries easier to parse and re-use in various ways by third-party applications
 * Use semantic HTML, improving reusability of Wikipedia content by both software and people
 * Will validate as both correct XHTML and HTML, ensuring the broadest browser compatibility (see for why this is important)
 * Are technically well-formed XML, another compatibility factor
 * Can be extended consistently, e.g. to include metadata, or to specially style terms and definitions
 * Will be easier to reconfigure if Wikipedia decides to change site-wide formatting, as it often does.

To produce a template-structured glossary, follow these simple steps:
 * 1) The glossary as a whole (or each part, if broken into sections, e.g. "A–M") is surrounded by a template and a corresponding  tag.
 * 2) A term is given on its own line using the template, and is automatically boldfaced.
 * 3) A definition is next given on its own line using the template, and follows either the term or a previous definition.

Do not make individual terms in a template-structured glossary into headings. Doing so will produce garbled output. The terms be linkable without being headings.

Use the templates as a set, and do not mix-and-match glossary templates with wikimarkup description list code ( and   style) or other markup.

If a glossary consists of only a few entries, with lengthy definitions, consider instead formatting the article as a subheading-style glossary, in regular paragraphs.

Formatting
Template-structured glossaries use semantic, accessible markup that adheres to Web standards, for reasons detailed above. Some example code, showing various formatting options, as might appear in a stand-alone glossary article divided into sections by letter of the alphabet:

{|class="wikitable" style="width: 90%;"
 * style="width: 50%; vertical-align: top;"|
 * style="width: 50%; vertical-align: top;"|

A–M
Optional introductory text.

term A: Beginning of the definition of term A. More of the definition of term A. term B: First definition of term B. Second definition of term B. term C: Simple definition of term C. term D: Definition of term D, with a... "Block-quoted passage."

More definition of term D.


 * style="width: 50%; vertical-align: top; background-color: white;"|

Optional introductory text.

term A: Beginning of the definition of term A. More of the definition of term A. term B: First definition of term B. Second definition of term B. term C: Simple definition of term C. term D: Definition of term D, with a... "Block-quoted passage."

More definition of term D.


 * }

As is shown in the example, multiple definitions use multiple templates. See the templates' documentation for the advanced features of, , and.

With template-structured (using these templates, or created manually with HTML), a definition behaves, inside its  bounds, just like normal prose and markup. Multiple paragraphs can be used with ease, and block-quotes, nested lists and other structures, unlike the other styles. The flexibility and power of HTML tags are much richer than those provided by wikimarkup's  and   description list or   unordered list features, which do not work properly due to MediaWiki bugs and misfeatures.

Multiple paragraphs can be created, as in regular prose, simply by introducing a blank line as shown in the example, or can be explicitly blocked out with markup.

Within a, all text and other content must be a. The following markup is invalid in several places, as annotated: thumb

Between definitions is no place for a quotation or anything else.

A paragraph (or whatever) can't be between entire entries, without to close the glossary before the content and a new to open glossary formatting again after that content being interpolated. Such add-on content does go inside the, which is just for the term and its markup.

Bullet-style
This is the simplest style used for glossaries. It is an application of a bulleted list. Example, with definitions next to terms:

This easy style is often used in embedded glossaries. Numbered lists (beginning with  instead of  ) should not be used, as they imply a specific (e.g. hierarchical or chronological) order.

Blocks of text, properly marked up, can be used for longer definitions. Multi-paragraph definitions require the HTML paragraph markup,  between either of the passages and the break, due to MediaWiki limitations (see /DD bug test cases for technical details). The markup is required both before and after the break or the line spacing will be noticeably inconsistent. Example, with definitions below terms:

Explicit elements can also be used instead of the  template, e.g.:

Remember to use the closing.

, as the output will be invalid markup, and the visual formatting will not be consistent (ordered and unordered lists indent further). Compare:

The HTML output of this is a trainwreck, especially for visually impaired users of screen-reader software, who are told, in series, that: an unordered list of one item has started; that list has ended; a description list with no term but one unassigned definition has started; that list ended; another unordered list of one item started, and ended; another description list with no term but two definitions unrelated to a term started, then ended; a third unordered list of one item started, and ended; a numbered list of two items, unassociated with the above material, started and ended; a fourth unordered list of one item started, then an embedded unordered list of two items started, then both ended. There is generally no clear relationship between any of the terms and definitions, or even a sense that this is one list of things that relate to each other in any way.

Subheading-style
Stand-alone glossaries with a limited number of mostly long and detailed definitions sometimes can be formatted best with entries as subheadings. One example of such a glossary is Glossary of ancient Roman religion. , as it will overwhelm the article's table of contents with glossary entries. It will also produce an overly-long ToC in a stand-alone glossary with a large number of entries. When this style is used, definitions are presented as normal prose paragraphs:

For cases in which most or all of the definitions are long, multi-paragraph explanations, this format is actually preferable to a template-structured glossary.

Multiple definitions are numbered manually, as shown; do not use ordered lists. This glossary type especially sometimes uses non-numeric identifiers with multiple definitions. Multi-paragraph definitions are just like any other Wikipedia prose paragraphs.

Semicolon-and-colon-style
The underlying, , and HTML elements (as generated in a template-structured glossary), are also what are output by wikicode lists formatted with initial   and   characters.

This markup style is very "brittle" and for glossaries, except of the shortest and simplest sort, as they are likely to have their semantic structure broken. Even something as simple as a blank line will break such a list.

General guidelines for writing glossaries
The following guidelines apply to all glossaries and should be followed regardless of which format style presented above is used. Wikipedia outlines, featuring entries with annotations in a hierarchical (classified) order, are not covered by these guidelines.

Alphabetize
In a glossary, alphabetize all the terms from A to Z. Entries must not be added randomly or in an arbitrary order. A Latin-based character with diacritics is alphabetized after the plain character it is based on. Non-Latin-based characters are alphabetized in order of their appearance in Unicode.

If numeral entries are present, they precede verbal ones, and any symbolic entries precede both (i.e.: "!" before "1" before "A"). Numeric entries that sometimes appear in the article subject's context as either numerals or spelled out verbally should be given in the form "three (3)" in short glossaries. In longer ones, it is more appropriate to create separate entries, put the definition in one, and crossreference the other entry to that one; put the definition in the verbal not numeral entry in most cases. If there is a definable difference in usage between the numeral and verbal terms in the context, use separate entries and distinguish between them with crossreferences.

If there are no symbolic and only one or a few numeral entries, it is permissible to alphabetize the numeral entries as if they were spelled out verbally, in the form "3 (three)", to avoid creation of a very short numeral entries section.

Make a separate section (or subsection) in a long stand-alone glossary article for each letter, but group them into ranges when appropriate, e.g. "X–Z". For shorter stand-alone glossaries, you may divide the entire article into ranges, e.g. "0–9", "A–M" and "N–Z", or use no divisions at all for very short cases (which may be candidates for merging into main articles on the subject). Do not section an embedded list, as this impedes editing and may greatly lengthen the overall article's table of contents; if an embedded list is long enough that it would benefit from sectioning, it is a good candidate splitting into a separate stand-alone glossary article. Do not create empty sections.

Alternatives
Glossary can be used for lists that are not strictly glossaries in the usual sense, and many of them will have non-alphabetic ordering rationales (e.g. chronological or geographical).

Use natural capitalization
In most glossaries, begin each glossary with a lower-case letter, unless it is a proper name or an acronym/initialism. While capitalizing the first letter of each term would produce a more uniform, outline-like result (which is why this is the standard for ordered and unordered lists on Wikipedia), natural capitalization produces fewer ambiguities in a glossary.

The use of leading capitals on all entries is recommended if all of the following apply simultaneously:
 * No term in the glossary is a lower-case form of something that in other contexts is usually capitalized
 * There is no difference between the capitalized and uncapitalized form of any term in the glossary
 * The terms do not contain a mixture of proper names and common nouns
 * Capitalizing all entries is otherwise unlikely to produce any form of ambiguity or confusion.
 * The glossary is unlikely to ever expand in a way that will break one of the above cases (i.e., it is either already exhaustive, is strictly limited by narrow inclusion criteria, or exclusively contains proper names).

Begin each with a capital letter, even if it is a sentence fragment.

The above does not apply to the use of description lists (with or without glossary templates) for material that does not form a glossary, such as list of characters, or an index of different models in a series of products.

What to include
Wikipedia is not a dictionary; correspondingly, explain glossary terms descriptively (just like a regular encyclopedia article would do it, but more concisely). Only rarely and sparingly add dictionary definitions to a glossary on Wikipedia (usually solely for the sake of completeness). Lists of dictionary definitions belong on Wiktionary; you can still link to them from Wikipedia articles.

Do not add everyday words. Include only specialized terms specific to or having a special meaning within the subject of the glossary.

All entries must be verifiable with reliable sources, just like regular article content.

The Wiktionary glossaries appendix project is likely to transwiki a copy of any glossary created on Wikipedia, and could considerably re-develop it in a more dictionarian direction. It is not necessary (and may be detrimental) to synchronize edits between the two versions, though it will be rare for an entry to be appropriate to exist at all in some form in only one version but not the other. The existence of a Wiktionary glossary on a topic that has a well-developed main article may be a good indication that an encyclopedic glossary on the subject may be developed, either using the dictionarian glossary as a base, or starting from scratch. If both versions do exist they should link to each other in their respective "See also" sections with a sister-project template, e.g. (see Wikimedia sister projects for recommendations about the best choice of template for various situations).

How to handle multiple variants of a term
One definition can actually have two or more terms above it as variations or alternatives with the same definition. The most common use case for this is presenting the term in two language variants. This is done with lang and the appropriate ISO language codes as described at that template. In template-structured glossaries, the bare term, without markup, must be the first parameter of term, and the language-markup version is parameter 2. If display of the language/dialect name is desired, the template family can be used instead of. Example: tire: tyre: A resilient wheel covering usually made of vulcanized rubber. Result:

tire: tyre: A resilient wheel covering usually made of vulcanized rubber.

The wikimarkup version is leaner, but has very limited functionality and cannot handle complex input: ; ;  :A resilient wheel covering usually made of vulcanized rubber.

How to handle multiple definitions
In a Wikipedia article, use consistent identifiers for two or more definitions of a term. In most cases, multiple definitions should be numbered. Other conventions exist, such as identification of the sub-field to which each definition pertains, but these are rarely mutually exclusive with numbering, and numerical identification is a convenient mnemonic for readers and referent for editors. Because articles may use numbers to distinguish among multiple definitions, avoid changing the order of definitions without good reason, and correct numerical references to definitions when you do change their order.

Outgoing links
Wikilinks to other pages or sections should generally not be used within the term in a description list, whether formatted with glossary templates or not. The rationales at apply equally well to description list terms, as they serve the purposes of both subheadings and list content. In template-structured markup, terms are themselves link targets; not all browsers properly handle content marked up both as a link target and an outgoing link anchor. Linking from inside a term should especially be avoided in actual glossaries, where the term's entry should stand on its own within that context. If there is more in-depth material at another page for the term in question, link to the term inline, or use an explicit cross-reference to that material.

Inline link:

baize: A coarse woolen cloth used to cover billiard tables, baize is usually green in colour. Sometimes called felt based on a similarity in appearance, though very different in makeup.

Cross-reference:

baize: A coarse woolen cloth used to cover billiard tables, usually green in colour. Sometimes called felt based on a similarity in appearance, though very different in makeup.

Hatnote:

baize: A coarse woolen cloth used to cover billiard tables, usually green in colour. Sometimes called felt based on a similarity in appearance, though very different in makeup.

Links within definition content are created as appropriate just like in any other encyclopedic prose content.

Incoming links
Anchors (points to which a link like  can directly point) can be created in bulleted, subheading-style, and wikimarkup (  and  ) glossaries, by using the  template.

Template-structured glossaries automatically (within certain limits) provide linkable terms ), and anchors can also be created for specific definitions, using template parameters.

Hatnotes, images, etc.
In bullet- and subheading-style glossaries, Hatnotes like and, images, and other material may be placed as desired.

Hatnotes cannot be used at all with wikimarkup ( and  ) glossaries, except before the start of the glossary and after its end. This also applies to all content marked up as a or other block element, such as sidebar templates that link to sister projects. Images can be added to the definition, but must be inline in it, without a link break.

In template-structured glossaries, hatnotes, images, and other such content must be placed within the definition – not between term and definition, nor between the last definition and the next term. Other than this restriction, all such content can be used normally inside the definition block. You may find the indentation of hatnote templates awkward-looking within a definition; the glossary-specific generic hatnote template removes that indentation.

Avoid semicolon-and-colon wikimarkup for glossaries
(with  and  ) for glossaries, as it is severely limited and buggy. While such lists are okay for very casual indented list creation, the MediaWiki software does not handle complex definitions gracefully in this format, or permit blank lines between items without ruining the semantic markup. Existing examples should be converted to template-structured glossaries, since most of the work is already done.

Use the standard styles only
Use a glossary style defined above, not your own made-up formatting, such as a pseudo-list created with manual styling, or misuse of a numbered (ordered) list. We have list-formatting standards for several reasons, and failure to follow them may confuse readers and editors, hamper reusability of Wikipedia content, make automated processing more difficult, and introduce usability and accessibility problems.

In some cases, tables are better-suited to associating content than description lists, especially when there are multiple values for each item.

Layout
Glossary articles are expected to satisfy the same conditions as other articles; this will include a well-developed lead section, and references.

The default Wikipedia table of contents will not be very useful with most glossaries. One solution is:

__NOTOC__

or, if there are only alphabetical entries from A to Z, simply:

There are a number of variants; see the documentation for Template:Compact ToC.

Please note that the section headings must be created manually, as usual, and must exactly match the selected parameters.

Each section in a lengthy glossary page should terminate with another call to (or some other form of concise sectional navigation). Compact ToC can be used with various other parameters enabled to keep the display thin and linear and with a link to the top of the page, e.g.:

Depending upon the parameters set, there may be a section for entries beginning with numerals, with symbols, or both. If present, this section should "A" or whatever the first alphabetic section is ("A–M", etc.)  Entries that are commonly but not always found in numeric form should be given in this section  cross-referenced to it from its spelled-out name, or vice versa, not given duplicate definitions. Cross references are italicized. Example:

Naming conventions
For a glossary list article that consists of a simple lead and a glossary, the form Glossary of subject terms is preferred, with redirects to it from Glossary of subject, Subject terms, Subject glossary, Subject terminology, Subject jargon, Subject slang, and List of subject terms (the last one to comply with the more general naming convention of lists pattern of "List of subjects").

For an article that mostly consists of a glossary list but has well-developed prose material on the history and use of the terminology, or other such information (several paragraphs worth), the form Subject terms is preferred, with redirects to it from Glossary of subject terms, Subject glossary and the other names (remember that reader cannot guess whether or not the article has been developed in this way). The links from the "glossary"-named redirects may go directly to the glossary section, if the historical and other material is lengthy. For an article that is on the history, development, spread, etc. of the terminology as a body of a certain subject area's jargon (like legal, dance, etc., terminology generally), and may include an embedded glossary of key terms, prefer Subject terminology, again with all the redirects. It is reasonably likely that such an article will eventually split into a prose article and a stand-alone, more developed, glossary article over time.

For a glossary of terms and characters used in a work or series of works of fiction (i.e. a fictional universe), the form Glossary of work/series/franchise name terminology is preferred (again with redirects) since the terms form a that does not exist as terms in use outside that fictional context. Example: Glossary of His Dark Materials terminology.

The general advice at WP:Stand-alone lists (e.g. handling of nationalities, fictional subjects, etc.) includes glossaries as well, to the extent applicable.

The sub-articles of multi-page split glossaries should follow the guidelines at WP:Naming conventions (long lists) to the extent applicable. In short, they should be named as the original (main) glossary page, with the letter or range of covered letters of the alphabet (or numbers, etc.) following a colon after this title, e.g. Glossary of underwater basketweaving terms: A–M or Curling terms: N–Z. Per WP:Manual of Style, the to divide the range, not a hyphen (-), em-dash (—), minus (−) or other similar character; however, the hyphenated form of the article name (e.g. Curling terms: N-Z) must also exist as a redirect to the real article page (AnomieBOT will do this automatically). Type the en-dash in as  or click on it to the right of the "Insert" tab under the edit window; or see How to make dashes.

Specialized glossaries may require a different sort of name (including for multi-part glossaries' sub-articles), e.g. Glossary of computing terms: Unix and Linux, Glossary of computing terms: Microsoft Windows, etc.

See the "Embedded glossaries" and "Using glossary formatting in non-glossary lists" sections, below, for related naming issues.

Article growth and splitting
A glossary that becomes too long (more than about 400 KB) should be split into multiple articles. This is a higher suggested limit than for normal articles, because we generally do not expect readers to work their way through a glossary from head to tail, so their length need not be limited by attention span, and a glossary's primary purpose is linking to specific entries and, crucially, in-page searching, which is broken by splitting. On the other hand, very large articles take a longer time to load, especially for editing or previewing.

When necessary, glossaries should usually be split into roughly equal chunks, rather than attempting to convert to summary style, or thinning out by narrowing the subject of the glossary. For example, the first split of Glossary of underwater basketweaving terms could be into Glossary of underwater basketweaving terms: A–M and Glossary of underwater basketweaving terms: N–Z, but very long glossaries may need even more parts, and some glossaries will have some one letters' sections much longer than others. If there are terms beginning with numbers or symbols, they should go before A, in sections of their own, unless there are enough of them to warrant their own subarticle.

There are two good solutions for the original Glossary of underwater basketweaving terms title: In either case, the other chunks should have summaries of the full lead, so that multiple different leads do not evolve. The first method is simpler; the second is preferable for glossaries so long that they need more than three or four chunks, or list articles in glossary format but not in basic alphabetical order (bicycles by manufacturer, wars by year, etc.).
 * Have it redirect to the first chunk, and include the original lead there.
 * Have it as a disambiguation page, with a full lead, and links to all the chunks.

Care is needed in dividing glossaries into subarticles. Each subarticle must link with the ones before and after, and to the disambiguation page if there is one; Compact ToC can help with this. Each sub-article must have references section, and these should be checked to be sure they still work. In particular, the first instance of a named tag in each subarticle will need its own text and cannot simply be a  secondary   call. The  name for the same ref should not change from subarticle to subarticle.

Embedded glossaries
A glossary included within an article may occasionally be helpful for readers, either to understand an article's terminology better, to learn more about the terminology used in a field covered by the article, or both. It may also provide a glossary that can be linked to from related articles, unless and until such time as a stand-alone glossary is warranted.

Some guidelines on including glossaries within articles, in addition to the general guidelines above:
 * The glossary must be its own section, with a heading identifying it as a glossary (this is not only orderly, it allows the glossary to be linked to directly). The title of this section should conform to WP:Manual of Style – do not repeat the subject in the heading. It also should not use excess verbiage ("Glossary of key terms in the discipline", etc.) – keep it simple. A plain   is fine in most cases.
 * If the glossary would be 5 terms or fewer, it is probably better to define the terms concisely in context in the prose of the article, instead of using a glossary.
 * If the glossary would be 25 terms or more, it is probably better to create a stand-alone glossary article.
 * If the entries will be very detailed, it is probably better to use a stand-alone glossary; embedded entries should be concise.
 * Embedded glossaries should not use subheadings inside them (e.g. for letters of the alphabet), and should simply be editable as a single section. If it is large enough to need subsectioning, it should probably be a separate article.

The preferred method of creating an embedded glossary is to use the template-structured style, and put the glossary under a single, clearly labeled heading (e.g. ).  This requires a bit more work than bulleted lists, but it provides most of the benefits of a stand-alone, template-structured glossary, and makes it very easy to eventually move the glossary to its own page when the glossary grows longer.

Using glossary formatting in non-glossary lists
Glossary-style formatting is not limited to use in glossaries. There are other uses for the markup methods employed in glossaries. They can be used for data presentation purposes in other types of lists. For example, glossary-style formatting may work well for presenting a list of aircraft serial numbers along with their models and descriptions, using the same basic layout as glossaries.

For an article that is a non-glossary list that uses glossary formatting, follow the advice at WP:Stand-alone lists. For the naming of multi-page, split lists, see WP:Naming conventions (lists). Such lists sometimes need customized naming, if they are not naturally expressible as alphabetic or numeric ranges, e.g. List of automobiles: Chevrolet, List of automobiles: Ford, etc. Note, however, the standardized use of a colon, not a parenthetical, comma, dash, slash or other separator. However, when a natural-English descriptive phrase is available, this is usually preferred instead; the real articles corresponding to the previous examples are at List of Chevrolet vehicles and List of Ford vehicles.

Non-glossaries often need different sectioning (numerical, topical) than a glossary, and consequently may have different table of contents needs. For multi-page long lists, each sub-article needs inter-page navigation of some kind to other articles in the series. Some solutions include specialized compact tables of contents and custom navigation templates. Such lists may also have different section needs, e.g., by date in a list of events, instead of alphabetical.

Technical notes

 * 1) While most of us already understand that accessibility and usability are crucial, many are not aware that code validation, well-formedness, and semantic correctness are also important. Very trivial HTML syntax errors can cause rendering failures even in the parser of Wikipedia's robust MediaWiki server engine, and their effect on each of the numerous browser platforms and automated tools on the user end is unpredictable. This is not the 1995 World Wide Web; the standards actually matter today.
 * , and cannot be used for any but the simplest of glossaries without causing problems for both readers and editors. via the simple templates described here (or bare HTML in unusual cases with special requirements). The two biggest problems with the   and   markup are that even one blank line, for readability, between definitions leads to mangled markup (often not visible to graphical-browser users, but problematic per point #1, above, and very apparent in other applications, such as screen-readers for the visually impaired). Multi-paragraph and otherwise complex definitions can only be correctly achieved inside such markup in a way that makes them difficult to edit and maintain.  Both of these problems are eliminated by using the template-structured glossary formatting presented above.
 * 1) In wikimarkup definition lists, a blank line between (i.e. between the definition of one entry and the term of the next) to space the entries further apart is fine, and will not affect the semantics of the code or the output   and  (or manually inserted  tags) surround all of the entries (of the whole glossary, or of the section, if the glossary is sectioned) as a block. If these are omitted, MediaWiki will treat every term as its own, and output messy code that is semantically useless. However, even if an editor includes them, a later editor is very likely to remove them believing them to be redundant.

Actual HTML output of template-structured glossaries
For the technically minded, the following is an explanation of the actual HTML markup that will be rendered from the templates by the reader's browser (not counting various classes and other details that are supplied automatically by the MediaWiki web application, and with spacing cleaned up a little for human readability). The code validates, is structurally well-formed, and is semantically correct.


 * 1) and  together invoke the  description list HTML structure (called a definition list in HTML 4, and sometimes also called an association list); the "dl" shortcut is not available at this time, unfortunately
 * 2) a.k.a.  invokes the  description list term HTML element, with an embedded  defining instance of term element
 * 3) a.k.a.  invokes the  description list definition element


 * Example wikicode : :

term A: Definition 1. term B: First definition start. First definition conclusion. Second definition.


 * HTML represented (minus the CSS) : :


 * Rendered output : :

term A: Definition 1. term B: First definition start. First definition conclusion. Second definition.

The result is the same if you put the entire of   on one line, as long as  markup is used to introduce the paragraph break in the definition:

1. First definition start. First definition conclusion.

That is to say, the following mixture of HTML markup and MediaWiki markup, trying to use simple whitespace to create a paragraph break, no longer works inside  (and thus ), as of 2023 (and since around 2014):

1. First definition start.

First definition conclusion.

The result will be run together in the output: <dl><dt></dt>1. First definition start.

First definition conclusion.</dl>

This behavior is consistent with MediWiki failing to auto-paragraph inside other inline-block elements, including and. (Inline-block elements are those block elements that in WHATWG's recommendations, i.e. in pretty much every modern browser, default to a CSS value of .)