In general, form the plural of a noun by adding s. If the noun already ends in s, form the plural by adding es. This rule applies to proper nouns as well as common nouns.
Microsoft style
the Johnsons
the Joneses
Form the plural of an abbreviation by adding an s with no apostrophe.
Microsoft style
ISVs
DBMSs
If an abbreviation already represents a plural, do not add an s. For example, the abbreviation for Microsoft Foundation Classes is MFC, not MFCs.
Form the plural of a single letter by adding an apostrophe and an s. The letter itself (but not the apostrophe or the ending s) is italic.
Microsoft style
x’s
Form the plural of a number by adding an s with no apostrophe.
Microsoft style
486s
the 1950s
Do not add (s) to a word to indicate that it can be construed as either singular or plural unless you have no other choice. Such words may be difficult to translate because not all languages form plurals by adding a suffix to the root word. If a placeholder modifier can result at different times in a singular or a plural noun, use the plural form. A word to which (s) is added may also lead to mistranslation in machine-translated content.
Microsoft style
Wait for x minutes.
Not Microsoft style
Wait for x minute(s).
There is no fixed rule for forming the plural of words derived from Latin and Greek that retain their Latin or Greek endings. The singular forms typically end in -a, -us, -um, -on, -ix, or -ex. The plural forms often take the Latin or Greek plural endings, but they can also be formed like other English words. To verify the spelling of such plurals, see specific entries in the Microsoft Manual of Style, or see the American Heritage Dictionary.
Form the possessive of singular nouns and abbreviations by adding an apostrophe and an s. This rule applies even if the noun or abbreviation ends in s.
Form the possessive of plural nouns that end in s by adding only an apostrophe. Form the possessive of plural nouns that do not end in s by adding an apostrophe and an s.
Microsoft style
the encyclopedia’s search capabilities
an OEM’s products
a children’s encyclopedia
the articles’ links
It is all right to form possessives from acronyms and abbreviations, but avoid doing so unless the abbreviation refers to a person, such as CEO, or generically to an organization, such as ISV. It is always all right to use an of construction instead.
Do not use the possessive form of Microsoft. Do not use the possessive form of other company names unless you have no other choice. And do not use the possessive form of a product, service, or feature name. You can use these names as adjectives, or you can use an of construction instead.
Microsoft style
the Windows interface
Microsoft products, services, and technologies
Word templates
templates in Word
the dictionary in the spelling checker
the Send command on the File menu
the OEMs’ products
the products of OEMs
Not Microsoft style
Windows’ interface
Microsoft’s products, services, and technologies
Word’s templates
the spelling checker’s dictionary
the File menu’s Send command
Do not use the possessive form of a property, class, object, or similar programming element.
Microsoft style
the Color property of the Ball object
Not Microsoft style
the Ball object’s Color property
Pronouns based on possessives never take apostrophes. Correct forms are its, ours, yours, hers, his, and theirs.