Rationale
Article titles give the reader an idea of what they can expect within an article. A reader may have found your article with a search, through Recent Changes or in some other way that provides no context for the subject matter, so do him a favor and name your articles precisely.
If a word or phrase is ambiguous, and an article concerns only one of the meanings of that word or phrase, it should usually be titled with something more precise than just that word or phrase. For example, use Apollo program, Nirvana (band), Smoking pipe; rather than simply Apollo, Nirvana, Pipe. However, if the subject of the article is the primary meaning of the word or phrase, or if it is unlikely that the other meanings will have Wikipedia articles, then the article may be titled with that word or phrase alone. For more information, see Wikipedia:Disambiguation.
On the other hand, excessive precision should be avoided. For example, it would be inappropriate to name an article United States Apollo program (1961–1975) or Nirvana (Aberdeen, Washington rock band).
Minor spelling variations
If two or more page names differ only in small details of spelling (including use of diacritics and capitalization) it may be advisable to combine the pages or provide links between the pages to reduce confusion for readers and editors. Which action is appropriate depends on whether the similarly titled pages are discussing the same or different meanings of the title.
If the two titles have the same meaning
Example: chargé d'affaires vs. charge d'affaires
In this case the other naming conventions policies and guidelines should be used to determine the most appropriate spelling of the word, and make all other synonyms redirect to that spelling. Having multiple pages for the same topic is an undesirable content fork.
Note that the exact capitalization of the article's title in most cases does not affect search, so it is not necessary to create redirects from alternative capitalizations unless these are likely to be used in links. For more details, see Naming conventions (capitalization).
For guidelines on how to treat national spelling differences, which are also applicable to article naming, see the National varieties of English section in the Manual of Style.
If the two titles usually have a different meaning
Terms with clearly distinct meanings usually each have their own page.
Examples:
- Diacritics: canon vs. cañon; Vitória vs. Vitoria
- Capitalization: WASP vs. wasp; Red Meat vs. Red meat
- With or without hyphen(s): Saint-Louis vs. Saint Louis
In this case, try to avoid confusion, per the general principle: When a reader enters this term and clicks "Go", what article are they most likely expecting to view as a result?
If there is a reasonable chance a reader might have been looking for another meaning, use an appropriate disambiguation technique:
- Hatnotes: for example WASP and Wasp both have hatnotes directing readers to the other page.
- Disambiguation page: for example many acronyms (like PIN or FLA) lead to disambiguation pages. If a different capitalization is the topic of another Wikipedia article, don't forget to link that article from the disambiguation page.
- Adding a parenthetical (bracketed) disambiguator to the page name: for instance when both spellings are often or easily confused. Use Streets of London (song) and Streets Of London (computer game) instead of Streets Of London and Streets of London. (Common disambiguators are listed at User:Kevinkor2/Research into names of Wikipedia articles.)
See Wikipedia:Disambiguation for guidance on which disambiguation technique would be most appropriate in which case.