This is the part of Wikipedia's Manual of Style which covers when to format text in articles, such as which text should use boldface or italic type.

Boldface (text like this) is common in articles, but is considered appropriate only for certain usages.

To create it, surround the text to be boldfaced with triple apostrophes ('''blah blah''').

To denote importance, seriousness, or urgency using semantic markup, you can also use the HTML element <strong>...</strong>, or the template {{strong}} which may be used by screen readers and other accessibility software, though support for this element widely varies depending on the technology used and how it is configured by the end user (i.e., it may well have no effect at all on a given screen reader by default, but it may be useful to some people in certain circumstances).

Boldface is often applied to the first occurrence of the article's title word or phrase in the lead. This is also done at the first occurrence of a term (commonly a synonym in the lead) that redirects to the article or one of its subsections, whether the term appears in the lead or not (see § Other uses, below).

This is not a requirement: for instance, it will not be desirable in a case where a large number of terms redirect to a single article, e.g. a plant species with dozens of vernacular names.

In the following cases, boldface is applied automatically, either by MediaWiki software or by the browser:

• Subsection headings of level 3 and below (===Subheading===, ====Sub-subheading====, etc., markup). There are five heading levels used in writing articles (the top-level one being reserved for the auto-displayed page name).
• Terms in description lists (example: Glossary of the American trucking industry)
• Table headers and captions (but not image captions)
• A link to the page on which that link appears, called a self link

Manually added boldface markup in such cases will end up making excessive double-bold (900 weight) fonts.

Use boldface in the remainder of the article only in a few special cases:

• After following a redirect: Terms which redirect to an article or section are commonly bolded when they appear in the first couple of paragraphs of the lead section, or at the beginning of another section (for example, subtopics treated in their own sections or alternative names for the main topic – see § Article title terms, above).
• Mathematical objects which are sometimes written in boldface, such as vectors and certain special sets, such as the rational number symbol Q (see Wikipedia:Manual of Style/Mathematics § Blackboard bold for further details)
• In some citation formats, for the volume number of a journal or other multi-volume works.

Citation templates, such as Template:Citation, automatically supply all formatting (such as italic, boldface, and quotation marks).

HTML's <strong>...</strong> emphasis, which usually renders as boldface, can be used in quotations to represent material boldfaced in the original material. It can also be rendered with the {{strong|...}} template.

Avoid using boldface for emphasis in article text. Instead, use HTML's <em>...</em> element or the {{em|...}} template (which usually render as italic).

Avoid using boldface for introducing new terms. Instead, italics are preferred (see § Words as words). Avoid using boldface (or other font gimmicks) in the expansions of acronyms, as in United Nations (see Wikipedia:Manual of Style/Abbreviations § Acronyms for guidelines on acronym style). The same applies to over-explaining portmanteau terms; avoid clauses like Texarkana is named for Texas and Arkansas.

Although it is possible to put non-Latin alphabets such as Greek or Cyrillic in boldface, this should be avoided.

The <strong> ({{strong}}) markup is generally not appropriate in article text except in quoted material (see above), though it is common in project pages, template documentation, talk page discussions, and other non-article contexts.

Italic type (text like this) is produced with double apostrophes around the content to be italicized: ''...''. Italics, along with semantic emphasis (usually rendered as italics), are used for various specific purposes in Wikipedia, outlined below.

The use of italics for emphasis on Wikipedia should follow good English print style. The most accessible way to indicate emphasis is with the HTML <em>...</em> element or by enclosing the emphasized text within an {{em|...}} template. Italics markup (''...'', or <i>...</i>) is often used in practice for emphasis, but this use is not semantically correct markup, so emphasis markup is preferred. Italics markup is for non-emphasis purposes, such as for book titles and non-English language phrases, as detailed below.

Emphasis may be used to draw attention to an important word or phrase within a sentence, when the point or thrust of the sentence may otherwise not be apparent to readers, or to stress a contrast:

Gellner accepts that knowledge must be knowledge of something.

It may be preferable to avoid the need for emphasis by rewriting a sentence more explicitly. Use of emphasis more than once in a sentence is rarely helpful to readers, unless the emphasized terms are being directly compared (more often a words-as-words case for regular italics). See also: § Quotations, below.

Other non-emphasis uses of italics should use ''...'' markup, not <em> or {{em}} markup.

Do not use boldfacing for emphasis, as covered in § When not to use boldface above. Do not use underlining, all caps, or small caps for emphasis, as covered in § How not to apply emphasis below.

Italics should be used for the following types of names and titles, or abbreviations thereof:

• Major works of art and artifice, such as albums, books, video games, films, musicals, operas, symphonies, paintings, sculptures, newspapers, journals, magazines, epic poems, plays, television programs or series, radio shows, comics and comic strips. Medium of publication or presentation is not a factor; a video feature only released on video tape, disc or the Internet is considered a "film" for these purposes, and so on. (See WP:Manual of Style/Titles § Italics for details.)

Minor works (and any specifically titled subdivisions of italicized major works) are given in double quotation marks not italics, even when the title is not in English. (For details, see § When not to use italics.)

These cases are well-established conventions recognized in most style guides. Do not apply italics to other categories or instances because you feel they are creative or artful (e.g. game or sport moves, logical arguments, "artisanal" products, schools of practice or thought, etc.).

• Court case names: FCC v. Pacifica. (Case citation or law report information is presented in normal font.)

• Certain scientific names:
  • Genes (but not proteins encoded by genes).
  • Genera (and abbreviation thereof) and all lower taxa (including species and subspecies), but not higher taxa (e.g. family, order, etc.). The entire scientific name should be italicized, except where an interpolation is included in or appended to the name. (For details, see § Scientific names.)
• Named, specific vessels: proper names given to:
  • Ships, with ship prefixes, classification symbols, pennant numbers, and types in normal font: USS Baltimore (CA-68). Italicize ship names when they appear in the names of classes of ships (the Baltimore-class cruisers). (See Wikipedia:Naming conventions (ships) for more detail on ship and ship class titles.)
  • Aircraft: the Spirit of St. Louis
  • Spacecraft (including fictional): the Space Shuttle Challenger, Gaia space observatory, USS Enterprise NCC-1701, Constitution-class starships. Do not italicize a mission, series, or class except where it coincides with a craft's name: the Eagle was the Apollo 11 lunar lander; Voyager 2 was launched as part of the Voyager program.
  • Trains and locomotives: the City of New Orleans (train)

The vessels convention does not apply to smaller conveyances such as cars, trucks, and buses, or to mission names. Also, most real-world spacecraft and rockets at this time are not given proper names, thus Apollo 11, Saturn V, Falcon 9, etc. are not appropriate to apply to spacecraft.

Use piped linking to properly italicize in wikilinks: "USS Baltimore (CA-68), the lead ship of the Baltimore-class cruisers", is produced by [[USS Baltimore (CA-68)|USS ''Baltimore'' (CA-68)]], the lead ship of the [[Baltimore-class cruiser|''Baltimore''-class cruisers]]

Use italics when writing about words as words, or letters as letters (to indicate the use–mention distinction). Examples:

• The term panning is derived from panorama, which was coined in 1787.
• Deuce means 'two'. (Linguistic glosses go in single quotation marks.)
• The most common letter in English is e.

When italics could cause confusion (such as when italics are already being heavily used in the page for some other purpose, e.g., many non-English words and phrases), double quotation marks instead may be used to distinguish words as words ("Just Say No" was an advertising campaign). Quotation marks may also be used when a whole sentence is mentioned (The preposition in She sat on the chair is on; or The preposition in "She sat on the chair" is "on"). For very small characters by themselves, code style is helpful: . (this is produced by: <code>.</code>).

A technical or other jargon term being introduced is often being mentioned as a word rather than (or in addition to) playing its normal grammatical role; if so, it should be italicized or quoted, usually the former. This first occurrence of the term should also usually be linked if it has its own article (or section, or glossary entry) corresponding exactly to the meaning when used in the present article.

Italics may also be used where <dfn> tags or {{dfn}} templates mark a term's first use, definition, introduction, or distinguished meaning on the page. Note that <dfn> tags and {{dfn}} templates do not apply text formatting, so the italicization (or quoting) must be added if intended. For instance, in the Consciousness article:

If, however, a term is an alternative name for the subject of the article (often the target of a redirect), then boldface should be used in place of italics or quotation marks at such a first occurrence (see § Article title terms, above):

     The small forward (SF), also known as the three, is one of the five positions in a regulation basketball game.

Generally, use only one of these styles at a time (do not italicize and quote, or quote and boldface, or italicize and boldface) for words-as-words purposes. Exceptionally, two styles can be combined for distinct purposes, e.g. a film title is italicized and it is also boldfaced in the lead sentence of the article on that film (see WP:ITALICTITLE for additional requirements and guidance):

     Roundhay Garden Scene is a very brief silent motion picture...

Combined styles are also valid in articles about a term or when significant terms redirect to an article, as in:

     The "New World" is a term which is applied to...

Do not switch back and forth between styles in the same material (e.g., using italics for words as words in one paragraph, then quotes in another).

Wikipedia generally uses italics for words and phrases from non-English languages if they are written using the Latin alphabet. This does not apply to loanwords or phrases that see everyday use in non-specialized English, such as qi, Gestapo, samurai, esprit de corps, e.g., i.e., etc.—as these have become English-language vocabulary. Use the native spellings of non-English language vocabulary using the Latin alphabet, with or without diacritics—otherwise, you should anglicize their spelling. For example:

• Gustav I of Sweden liked to breakfast on crispbread (knäckebröd) open sandwiches with toppings such as messmör (butter made from goat's milk), ham, and vegetables.
• Code: [[Gustav I of Sweden]] liked to breakfast on [[crispbread]] ({{lang|sv|knäckebröd}}) open sandwiches with toppings such as {{lang|sv|messmör}} (butter made from goat's milk), ham, and vegetables.

The {{lang}} template and its variants support all ISO 639 language codes, correctly identifying the language and automatically italicizing for you. Please use these templates rather than manually italicizing non-English material. (See WP:Manual of Style/Accessibility § Other languages for more information.)

Use non-English vocabulary sparingly; for more information, see Wikipedia:Writing better articles § Use other languages sparingly. Certain specialist or non-English terms are not italicized, including musical terminology like minuet and adagio. As a rule of thumb, do not italicize words that appear in multiple major English dictionaries.

If it is necessary to include terms written in a non-Latin script, they can be placed in parentheses. Text in non-Latin scripts (such as Greek, Cyrillic or Chinese) should neither be italicized as non-English nor bolded, even where this is technically feasible; the difference of script suffices to distinguish it on the page. However, titles of major works that should be italicized are italicized in scripts that support that feature (including Latin, Greek and Cyrillic); do not apply italic markup to scripts that do not (including Chinese, Japanese, and Korean).

Some proper names—including personal names, place names, and the names of organizations—are usually not italicized as non-English vocabulary. However, these may be italicized for other reasons, including when the name itself is being referred to. For example, non-English names listed as translations in the lead of an article should be italicized, e.g. Nuremberg (German: Nürnberg). Non-English names of works should be italicized just like those in English are, e.g. Les Liaisons dangereuses. When a name should not be italicized, language markup can still ensure proper pronunciation in screen readers, by using the |italic=unset parameter: {{lang|de|italic=unset|Nürnberg}}.

For better accessibility, Latin quotations should not be set in all caps or small caps. When reproduced for their content, inscriptions that were originally set in all caps should be transcribed according to standard rules of English capitalization. Please note, however, that simply undoing caps may result in incorrect orthography; for example, capital V may represent either the consonant v or the vowel u. All-caps or preferably small-caps presentation may be preserved when it is contextually useful, as in technical linguistic material and descriptions of artifacts. Editors should be cautious about making their own interpretations when transcribing epigraphic and numismatic sources. Particularly on coins, a character that appears to be a letter may instead be a Roman numeral, a denomination, or a symbol. For articles that reproduce examples of epigraphy or coin legends, editors should consult the orthography of expert secondary sources (see also diplomatic transcription).

Scientific names of organisms are formatted according to normal taxonomic nomenclature.

• Do not italicize (but do capitalize) taxa higher than genus (exceptions are below).
  • Virus taxonomy is a partial exception; current scientific practice is to italicize all ranks of taxa (even those higher than genus; e.g., Ortervirales, an order, or Herpesviridae, a family). However, this should only be done in articles about viruses or virology; mentions of virus taxa in articles about other forms of life should follow the normal rules for italicizing scientific names.
• Italicize all lower ranks (taxa): genus (capitalized), subgenus (capitalized), species, subspecies.
  • Names of genera are always italicized (and capitalized), even when not paired with a species name: Allosaurus, Falco, Anas.
  • The entire binomial or trinomial scientific name is italicized, whether given in full or abbreviated: (Liriodendron tulipifera, N. v. piaropicola).
• Interpolations such as "cf.", "×", "var.", or "subsp." are not italicized: Ninox cf. novaeseelandiae, the chaussie is a hybrid cat (Felis catus × F. chaus).
• Parenthetic expressions should not be italicized unless part of the scientific name, as in the case of a subgenus, which is always italicized, though the parentheses (round brackets) are not: Potentilla (Sibbaldiopsis) tridentata.
• Do not italicize authorities (author names) juxtaposed with scientific names: Subgenus Potentilla Syme and subgenus Hypargyrium (Fourr.) Juz. have been combined under subgenus Potentilla Syme. In the article body, wrap the authority information in {{small}} or <small>...</small>. (This need not be done for authorities in a taxobox that are entered using parameters such |authority= or |parent_authority=, since small text is then used automatically. For synonym lists, either use templates like {{Species list}} which automatically use small text for authorities, or wrap the authority information as described above.)

Derived uses in non-biological contexts are not italicized: The largest carnivore in family Tyrannosauridae was T. rex itself, but Unicorn was an album by the band T. Rex.

Although often derived from Latin or Ancient Greek, scientific names are never marked up with {{lang}} or related templates.

Do not put quotations in italics. Quotation marks (or block quoting) alone are sufficient and the correct ways to denote quotations. Italics should only be used if the quoted material would otherwise call for italics.

Use italics within quotations to reproduce emphasis that exists in the source material or to indicate the use of non-English words. The emphasis is better done with {{em}}. If it is not clear that the source already included italics (or some other styling) for emphasis, or to indicate when emphasis was not used in the original text but was editorially added later, add the editorial note [emphasis in original] or [emphasis added], respectively, after the quotation.

• For example: "Now cracks a noble heart. Good night sweet prince: And flights of angels sing thee to thy rest." [emphasis in original].

Variables in computer programs and symbols for program variables within plain-English prose and in computer source code presented as textual content can be marked up with the {{var}} template:

• ...where {{var|x}} is incremented on each pass... ⇒ ...where x is incremented on each pass...
• |id={{var|ISBN or other identifier}} ⇒ |id=ISBN or other identifier

This provides richer semantic markup over simple italicization (or no formatting at all), that can aid in searching, accessibility, and disambiguation between variables and literal values.

<math>...</math> LaTeX markup produces a serif font, unlike the default sans-serif prose font. To avoid confusion over the meaning of symbols, use math templates that put math expressions in a serif font. This also makes it easier to distinguish between I (upper-case i) and l (lower-case L), which look almost identical in many sans-serif fonts. Math variables are always written in italics. For standalone references to math variables, use {{mvar}}, which will render in an italic serif font. For math equations, use {{math}}. For variables within {{math}}, use double apostrophes to make italics.

• The value of {{mvar|y}} is always... ⇒ The value of y is always...
• {{math|''E'' {{=}} ''mc''<sup>2</sup>}} ⇒ E = mc

Some things remain in upright form regardless of the surrounding text

• Bold-face variables (such as vectors) and structures (such as Q, the rational numbers)
• Letters with an arrow on top for vectors
• Symbols for chemical elements and compounds such as HCl
• Symbols for units of measure such as kg, ft/s
• Symbols for mathematical operators such as sin and ln; for example:

  sin x, ln (p/p₀)

One-line notes that are placed at the top of articles or sections (most often to assist disambiguation or provide cross-references) are hatnotes. One-line notes may also be placed at the top of sections to cross-reference or point to additional information that is not directly linked in the text. Both of these are in italics and indented to distinguish them from the text of the article proper. The Disambiguation and redirection templates and Wikipedia page-section templates automatically provide the required italic formatting.

Special section headings for appendices such as ==See also== are not in italics.

A further type of cross-reference may occur within a paragraph of text, usually in parentheses (round brackets). For example: At this time France possessed the largest population in Europe (see Demographics of France). Here, the cross-referenced article does not topically make a good target for a running-text link from the phrase "largest population in Europe", or any other text in the sentence, but has been deemed relevant enough to mention in passing without relegating it to the "See also" section at the bottom of the article. These kinds of cross-references can be formatted easily with the {{Crossreference}} a.k.a. {{Crossref}} template (or, to other sections on the same page, {{See above}} and {{See below}}). In any case where such a link in running text would be proper, it is preferred over a parenthetical, explicit cross-reference.

Like hatnotes, these parenthetical cross-references are set off by being italicized in their entirety, as Wikipedia self-references, and not part of the article content proper. Unlike some traditional reference works, the convention that has evolved on Wikipedia is not to individually italicize "see" or "see also". Wikipedia's own article titles are not put in quotation marks in such cross-references.

Italics are generally used only for titles of longer works. Titles of shorter works should be enclosed in double quotation marks ("text like this"). This particularly applies to works that exist as a smaller part of a larger work. These include but are not limited to: articles, essays, papers, chapters, reference work entries, newspaper and magazine sections or departments, episodes of audio-visual series, segments or skits in longer programs, short poems, short stories, story lines and plot arcs; songs, album tracks and other short musical works; leaflets and circulars.

Italics should not be used for non-English text in non-Latin scripts, such as Chinese characters and Cyrillic script, or for proper names, to which the convention of italicizing non-English words and phrases does not apply; thus, a title of a short non-English work simply receives quotation marks.

Avoid various kinds of overemphasis, other than the recommended one (see: MOS:EMPHASIS), which would distract from the writing:

• Exclamation points (!) should usually only be used in direct quotes and titles of creative works.
• Bold type is reserved for certain uses.
• Quotation marks for emphasis of a single word or phrase are incorrect, and "scare quotes" are discouraged. Quotation marks are to show that you are using the correct word as quoted from the original source. For example: His tombstone was inscribed with the name "Aaron" instead of the spelling he used during his life.
• Avoid using ALL CAPS and small caps for emphasis (for legitimate uses, see WP:Manual of Style/Capital letters § All caps). Italics are usually more appropriate.
• Double emphasis, such as italics and boldface, "italics in quotation marks", or italics and an exclamation point!, is unnecessary.
• Underlining is used in typewriting and handwriting to represent italic type. Generally, do not underline text or it may be confused with links on a web page.
• Do not capitalize words merely as a form of emphasis or signification.

Editors should avoid manually inserting large and small fonts into prose. Increased and decreased font size should primarily be produced through automated facilities such as headings or through carefully designed templates.

Reduced or enlarged font sizes should be used sparingly, and are usually done with automated page elements such as headings, table headers, and standardized templates. Size changes are specified as a percentage of the original font size and not as an absolute size in pixels or point size. This improves accessibility for visually impaired users who use a large default font size.

Avoid using smaller font sizes within page elements that already use a smaller font size, such as most text within infoboxes, navboxes, and references sections. This means that <small>...</small> tags, and templates such as {{small}} and {{smalldiv}}, should not be applied to plain text within those elements. In no case should the resulting font size of any text drop below 85% of the page's default font size. Note that the HTML <small>...</small> tag has a semantic meaning of fine print or side comments; do not use it for stylistic changes.

For use of small text for authority names with binomials, see § Scientific names.

Prose text should never be colored. Refrain from implementing colored links that may impede user ability to distinguish links from regular text, or color links for purely aesthetic reasons. See also Wikipedia:Manual of Style/Linking.

1. Colors used in templates such as navboxes and infoboxes, and in tables, should not make reading difficult, including for colorblind or otherwise visually impaired readers.
2. Colors that are useful for identification and are appropriate, representative, and accessible may be used with discretion and common sense. In general, text color should not be anything other than black or white (excluding the standard colors of hyperlinks), and background colors should contrast the text color enough to make the template easily readable. See Wikipedia:Manual of Style/Accessibility/Colors for more information.
3. An "appropriate, representative" color, when intended to identify with an organization's logo or branding, should use the most prominent accessible color in the logo. For example, Template:Pink Panther should be using a background of F6D4E6   (the color of the body in File:Pink Panther.png) rather than E466A9   (the color of the background in that image). A representative color useful in a navbox is often already present in an article's infobox (if included), and these are sometimes specified programmatically. For example, the navbox associated with the National Register of Historic Places and other related categorizations should conform to Wikipedia's NRHP colors legend.
4. In the case that no properly identifying, accessible color exists; or the subject of the template or table should not be identified with a particular color (e.g., an average biography), the default colors provided by the template or the table class should be used.
5. If an article includes several navboxes whose colors conflict with each other, discretion should be used to minimize the visual disruption by using the default colors for navboxes.
6. Content should also be easy to read in dark mode, preferably without a large area of bright background. This can be accomplished by removing color styling and using the default skin colors, by picking colors that work well in both light and dark mode, or by setting different colors for each mode using techniques from the official MediaWiki recommendations.

Font families should not be explicitly defined in an article, with the exception of PUA characters (next section), because this interferes with Wikipedia's flexibility, and it is impossible to foresee what fonts will be installed on a user's computer.

Articles used to explicitly define font families for special characters, because older browsers could not automatically select an appropriate font. This is no longer dealt with by using explicit font definitions in the articles. Certain definitions can be invoked by using special templates (see Help:Special characters, and templates listed at Template:Unicode).

The use of capital (upper-case) letters, including small-capitals style, is covered in detail at WP:Manual of Style/Capital letters.

Text formatting in citations should follow, consistently within an article, an established citation style or system. Options include either of Wikipedia's own template-based Citation Style 1 and Citation Style 2, and any other well-recognized citation system.

Parameters in the citation templates should be accurate. Do not evade the formatting applied by a parameter, e.g. by using markup tricks or by switching to an inapplicable parameter simply because its style of output is different. A parameter with useful citation data should not be omitted just because the auto-applied style is not in agreement with text-formatting guidelines; that is a template bug to fix.

Do not use strikethrough to indicate inappropriate or incorrect material; this causes accessibility and comprehensibility problems, and there are several better alternatives, including commenting out, deletion, and tagging for discussion. Intentional use of strikethrough as part of the content is discouraged for similar reasons. If strikethrough is used to indicate deleted text, such as in textual analysis, it should be implemented with semantic HTML element <del> and combined with other techniques for accessibility purposes.

The only invisible characters in the editable text should be spaces and tabs. However, other invisible characters are often inserted inadvertently by pasting from a word processor, from the rendered Wikipedia page (in some browsers), or from Wikipedia's Android editor. These can cause confusion with editors and handling problems with editing software. Any necessary invisible or Private Use Area (PUA) characters should be substituted with their decimal or hexadecimal code values (that is, as &...;) so that they can be edited properly. A template, {{PUA}}, is used to mark PUA characters; it has no effect on the text, but places the article in a tracking category. (See the next sections for examples.)

When right-to-left text is embedded in certain left-to-right contexts, such as when tagged with a reference, it may require control characters to display properly. The marker to return to left-to-right text should be encoded as &lrm; or supplied through the template {{lang}}.

Depending on your browser, there may be a difference between the display of unformatted Urdu:

خ ?<ref>citation details</ref>:   خ ?

with formatted:

خ&lrm; ?<ref>citation details</ref>:   خ‎ ? or {{lang|ur|خ}} ?<ref>citation details</ref>:   خ ?

and unformatted:

(خ)<ref>citation details</ref>:   (خ)

with formatted:

(خ)&lrm;<ref>citation details</ref>:   (خ)‎ or {{lang|ur|(خ)}}<ref>citation details</ref>:   (خ)

If there is intervening LTR text, as in خ abc<ref>citation details</ref>, a control character is not required. Spacing and most punctuation, however, are not defined as either LTR or RTL, so the direction of the text needs to be reset manually.

Private Use Area (PUA) characters are in three ranges of code points (U+E000–U+F8FF in the BMP, and in planes 15 and 16). PUA characters should normally be avoided, but they are sometimes used when they are found in common fonts, especially when the character itself is the topic of discussion.

Where PUA characters cannot be replaced with non-PUA Unicode characters, they should be converted to their (hexa)decimal code values (that is, &#...; or &#x...;). However, whenever a PUA character has a Unicode equivalent, it should instead be replaced with that equivalent (Unicodified). The Unicode may be obvious when text is copied and pasted from a document that uses the PUA for bullets or similar characters in Latin text, but similar things happen with punctuation and emoticons in documents using Japanese and other scripts, so an editor familiar with those scripts may be needed. In Chinese documents it is not uncommon for the PUA to be used for characters that now have full Unicode support, due to poorer support for Chinese characters when those fonts were designed. Such PUA characters, which are sometimes found on Wikipedia in references and footnotes, should not be substituted with their (hexa)decimal values, as that will lock in the illegible character. If you're moderately familiar with the script, an internet search of the surrounding text will often locate a fully Unicode version of the text which can be used to correct the Wikipedia article.

Because browsers do not know which fonts to use for PUA characters, it is necessary for Wikipedia to specify them. Formatting via one of the templates listed at Template:Unicode is sufficient in some cases. Otherwise the fonts should be specified through html markup, as in the example below. Note that if a font is not specified, or if none of the fonts are installed, readers will only see a numbered box in place of the PUA character.

Tagging a (hexa)decimal code with the template {{PUA}} will enable future editors to review the page, and to Unicodify the character if it is included in future expansions of Unicode. This happened, for example, at strident vowel, where a non-Unicode symbol for the sound was used in the literature and added to the PUA of SIL's IPA fonts. Unicode didn't support it until several years after the Wikipedia article was written, and once the fonts were updated to support it, the PUA character in the article was replaced with its new Unicode value.

For example,

SIL added these letters at U+F267 and U+F268: <span style="font-family:Gentium Plus, Charis SIL, Doulos SIL, serif">{{PUA|&#xf267;}}, {{PUA|&#xf268;}}</span>.

which renders as:

SIL added these letters at U+F267 and U+F268: , .

See Category:Articles with wanted Private Use Area characters and especially Tengwar § Unicode for examples of PUA characters which cannot easily be replaced.

• WP:Advanced text formatting
• WP:Manual of Style/Capital letters
• WP:Manual of Style/Command-line examples
• WP:Manual of Style § Ligatures
• WP:Superfluous bolding explained (essay)