Wikipedia:Naming conventions (capitalization)

Do not capitalize the second or subsequent words in an article title, unless the title is a proper name. For multiword page titles, one should leave the second and subsequent words in lowercase unless the title phrase is a proper name that would always occur capitalized, even mid-sentence.

This convention often also applies within the article body, as there is usually no good reason to use capitals. Outside Wikipedia, and within certain specific fields (such as medicine), the usage of all-capital terms may be a common way to feature new or important items. However, these cases are typically examples of buzzwords, which by capitalization are (improperly) given special emphasis.

For details on when to capitalize on Wikipedia, see the Wikipedia Manual of Style sections on capital letters and, when relevant, on trademarks. When in doubt, reliable reference works for capitalization conventions and other style matters may be useful. Note that all style guides conflict on some points; the Wikipedia MoS and naming conventions are a consensus-based balance between them, drawing primarily upon academic style, not journalistic or marketing/business styles, and taking into account Wikipedia-specific concerns.

Software characteristics
The software treats all page titles as beginning with a capital letter (unless the first character is not a letter). For information on how to display article titles beginning with lower-case letters (as in eBay), or category titles (as in Category:macOS) see.

However, when you create a link with the first letter of the link uncapitalized, as in swimming pool, the first letter of the is automatically capitalized in the URL by the software, thus going to the article Swimming pool in this example. However, the remainder of the link (after the initial character) case-sensitive.

Searching using the Go or Search button is, generally speaking, case-insensitive. It is not necessary to create redirects from alternative capitalizations, unless editors are likely to link from the differently capitalized form. For example, National Park should be created as a redirect to National park, but it is unnecessary to create Isle of wight as a redirect to Isle of Wight. Many such redirects do nevertheless exist, and these are harmless; the only indication to the reader is a small message of the form "(redirected from Isle of wight)". You can use a page-views analysis tool to determine whether a significant number of people ever look for the variant you are thinking of creating a redirect for, or what the frequency of one version is versus another.

Page names that differ only by capitalization
It is occasionally acceptable to create two articles (on different topics) with titles that differ only in capitalization, such as Duck sauce and Duck Sauce. If this arises, place a hatnote at the top of each page, linking each to a dedicated disambiguation page or to the other article. It is also acceptable to use names that are differentiated in other ways; which approach should be taken may vary from case to case, balancing such considerations as the risk of confusion in using one set of names against the departure from brevity and common usage in using the other.

Titles of works
In general, each word in English titles of books, films, and other works takes an initial capital, except for articles ("a", "an", "the"), the word "to" as part of an infinitive, and prepositions and coordinating conjunctions shorter than five letters (e.g., "on", "from", "and", "with"), unless they begin or end a title or subtitle. Examples: A New Kind of Science, Ghost in the Shell, To Be or Not to Be, The World We Live In.

Organisms
English common names of species and of general types of organisms are not capitalized, and article titles about them are sentence-cased, except where proper names appear and are capitalized: Bottlenose dolphin, Livestock guardian dog, Red oak, but Small Indian civet. Redirects should be created from the alternative capitalized form(s), e.g., Bottlenose Dolphin, and from plural forms of each spelling.

Capitalization of expressions borrowed from other languages
For French, see for instance. In French, the capitalization rules (for books, works of art, and many other topics) are different from those in English. The situation is further complicated by loanwords, for example a French expression can be adopted in English (such that you'll find it in English dictionaries), but with a different capitalization:
 * Art Nouveau is how the name of a certain art movement is most often written in English; but is how it is written in French.

Expressions
For expressions borrowed from other languages a two-step approach is advised (example explained for expressions borrowed from French): For Spanish, German, and any language usually written in the Latin alphabet the same (or something similar) would apply.
 * Check whether or not a French expression has been adopted in English as a loan word: if it is, follow the usual English capitalization rules, as explained in other parts of this page.
 * If the French expression is untranslated (not a loanword), follow French capitalization practice. For French: some expressions are not capitalized at all (e.g., fin de siècle), others have a capitalization of the first word.

Works and compositions
If the article is about a creative or academic work (such as a book or other written work, movie, album, song, or composition) with a title in a foreign language, or by a non-English-speaking creator, retain the style of the original for modern works. For historical works, follow the dominant usage in modern, English-language, reliable sources.

Examples

 * Multiword articles: Practical joke, Particle physics, 1993 Russian constitutional crisis
 * Proper names: North America, William Shakespeare, International Phonetic Association
 * Proper names within article titles: History of the Soviet Union (1982–1991), Politics of the United States
 * Titles of books and other works: A New Kind of Science, Ghost in the Shell, Oliver Twist. Such titles often need to be italicized;.