Wikipedia:Simplified Manual of Style

This Simplified Manual of Style is an overview of commonly used style guidelines taken from the Manual of Style and its subpages (together called the MoS). When a MoS guideline offers a choice of style, use only one alternative consistently throughout an article, and do not unreasonably alter a choice that has already been made. The MoS has too many suggestions to memorize, or even to consult regularly, but because they are based on consensual discussion, they often settle time-wasting arguments. Wikipedia has no firm rules, but these suggestions help create consistent articles. For a descriptive directory of the pages which make up the Manual of Style, see Manual of Style/Contents.

Capital letters
Use sentence case for article titles and section headings – Tips and pointers, not Tips and Pointers.

Capitalize names of scriptures like Bible and Qur'an, but not biblical. Always capitalize God when it refers to a primary or only deity, but not pronouns that refer to deities: he not He.

Avoid capitalizing names of plants and animals. Among the exceptions are scientific names (Felis catus) and proper nouns occurring as part of a name (Norway rat).

The seasons (summer, winter, spring, and fall/autumn) are not capitalized. Similarly, the compass points (north, southwest) are not capitalized.

When in doubt about whether to capitalize something, the general rule is that Wikipedia only capitalizes that which is capitalized in the vast majority of source material. If sources veer between upper- and lower-case for something, then default to lower-case.

Abbreviations
To indicate approximately, the non-italicized abbreviation c. (followed by a space) is preferred over circa, ca., or approx.

Write US or U.S., but not USA. Use US, not U.S., in an article using UK, PRC, etc.

Use "and" instead of the "&" sign, except in tables, infoboxes, and official names like AT&T.

Apostrophes and quotation marks
Use straight quote marks " and apostrophes ' as available from the keyboard, and not alternatives such as “ ” and ‘ ’.

Italicize names of books, films, TV series, music albums, paintings, and ships—but not short works like songs or poems, which should be in quotation marks.

Write James's house, not James' house.

Periods and commas
Place a full stop (a period) or a comma before a closing quotation mark if it belongs as part of the quoted material; otherwise put it after: The word carefree means "happy". But: She said, "I'm feeling carefree. " (Please do so irrespective of any rules associated with the variety of English in use.)

An ellipsis should be written as three separate dots (...): not spaced (. ..), and not using the single-character option (…).

The serial comma (for example the comma before and in "ham, chips, and eggs") is optional; be sensitive to possible ambiguity from thoughtless use or thoughtless avoidance.

Avoid comma splices.

Picture captions should not end in a full stop (a period) unless they are complete sentences.

Dashes and hyphens
Avoid using a hyphen after a standard -ly adverb (a newly available home).

A hyphen is not a dash. Hyphens are used within words or to join words, but not in punctuating the parts of a sentence. Use an en dash (–) with  before and a space after; or use an em dash (—) without spaces. See How to make dashes. Avoid using two hyphens (--) to make a dash; and avoid using a hyphen for a minus sign.

Use an en dash, not a hyphen, between numbers: pp. 14–21; 1953–2008. An en dash is also to connect parallel terms: red–green colorblind; a New York–London flight. Use spaces around the en dash only if the connected terms are multi-unit dates: January 1999 – December 2000.

Dates and numbers
Write number 1 or No. 1, but not #1. Comic books are an exception. Do not use the symbol №.

Write 12,000 for twelve thousand, not 12.000.

Both 10 June 1921 and June 10, 1921, are correct, but should be consistent within an article. A comma is not used if only the month is given, such as June 1921.

400 AD (or AD 400) and 400 BC are correct; but so are 400 CE and 400 BCE. As always, use one style consistently in an article.

Use one, two, three, ..., eight, nine in most cases, not 1, 2, 3, 4, 5, 6, 7, 8, 9 (exceptions include times and dates, equations, sport scores, most measurements, and data in tables). Use digits for 10 and higher (though some such numbers also may be written as words, when it helps clarity).

Markup
Instead of an ordinary space, use  (a non-breaking space) to prevent a line from ending in the middle of expressions like 17 kg, 565 BCE, 2:50 pm, £11 billion, 129 million, July 2024, 5° 24′ 21.12″ N, or Boeing 747; also after the number in 123 Fake Street, and before Roman numerals in World War II and Pope Benedict XVI. Use  in the same way inside a wikilink. (An alternative: enclose the whole expression using the template nowrap.)

It does not matter how many spaces come after a period because extra spaces will not show, although blank lines will create one extra line.

Use wikilinks, but only for words and phrases that are most likely to be helpful if clicked. Make sure each link goes to an article on the intended subject, and not to a disambiguation page or incorrect destination.

Usage
English Wikipedia prefers no major national variety of the language over any other. These varieties (e.g. U.S. English, British English) differ in vocabulary (soccer vs. football), spelling (center vs. centre), and occasionally grammar.

Avoid words like I, we, and you, except in quotations and names of works.

Avoid phrases like note that and remember that (which assume "you" for the reader); and avoid such expressions as of course and obviously.