Apostrophes

Rule 1a. Use the apostrophe to show possession. To show possession with a singular noun, add an apostrophe plus the letter s.

Rule 1b. Many common nouns end in the letter s (lens, cactus, bus, etc.). So do a lot of proper nouns (Mr. Jones, Texas, Christmas). There are conflicting policies and theories about how to show possession when writing such nouns. There is no right answer; the best advice is to choose a formula and stay consistent.

Rule 1c. Some writers and editors add only an apostrophe to all nouns ending in s. And some add an apostrophe + s to every proper noun, be it Hastings's or Jones's.

One method, common in newspapers and magazines, is to add an apostrophe + s ('s) to common nouns ending in s, but only a stand-alone apostrophe to proper nouns ending in s.

Care must be taken to place the apostrophe outside the word in question. For instance, if talking about a pen belonging to Mr. Hastings, many people would wrongly write Mr. Hasting's pen (his name is not Mr. Hasting).

Another widely used technique is to write the word as we would speak it. For example, since most people saying "Mr. Hastings' pen" would not pronounce an added s, we would write Mr. Hastings' pen with no added s. But most people would pronounce an added s in "Jones's," so we'd write it as we say it: Mr. Jones's golf clubs. This method explains the punctuation of for goodness' sake.

Rule 2a. Regular nouns are nouns that form their plurals by adding either the letter s or es (guy, guys; letter, letters; actress, actresses; etc.). To show plural possession, simply put an apostrophe after the s.

Rule 2b. Do not use an apostrophe + s to make a regular noun plural.

In special cases, such as when forming a plural of a word that is not normally a noun, some writers add an apostrophe for clarity.

In that sentence, the verb do is used as a plural noun, and the apostrophe was added because the writer felt that dos was confusing. Not all writers agree; some see no problem with dos and don'ts.

However, with single lowercase letters, it is advisable to use apostrophes.

Imagine the confusion if you wrote that sentence without apostrophes. Readers would see as and us, and feel lost.

Rule 2c. English also has many irregular nouns (child, nucleus, tooth, etc.). These nouns become plural by changing their spelling, sometimes becoming quite different words. You may find it helpful to write out the entire irregular plural noun before adding an apostrophe or an apostrophe + s.

Rule 2d. Things can get really confusing with the possessive plurals of proper names ending in s, such as Hastings and Jones.

If you're the guest of the Ford family—the Fords—you're the Fords' guest (Ford + s + apostrophe). But what if it's the Hastings family?

Most would call them the "Hastings." But that would refer to a family named "Hasting." If someone's name ends in s, we must add -es for the plural. The plural of Hastings is Hastingses. The members of the Jones family are the Joneses.

To show possession, add an apostrophe.

In serious writing, this rule must be followed no matter how strange or awkward the results.

Rule 2e. Never use an apostrophe to make a name plural.

Rule 3. With a singular compound noun (for example, mother-in-law), show possession with an apostrophe + s at the end of the word.

If the compound noun (e.g., brother-in-law) is to be made plural, form the plural first (brothers-in-law), and then use the apostrophe + s.

Rule 4a. If two people possess the same item, put the apostrophe + s after the second name only.

However, if one of the joint owners is written as a pronoun, use the possessive form for both.

Note: As the above examples demonstrate, when one of the co-owners is written as a pronoun, use possessive adjectives (my, your, her, our, their). Avoid possessive pronouns (mine, yours, hers, ours, theirs) in such constructions.

It should be mentioned that compound possessives are often clunky as well as confusing. For instance, a picture of her and Cesar's house could refer to a photo of "her" in front of the house that Cesar owns or a photo of the house that she and Cesar co-own. Big difference. Such ambiguous sentences should just be rewritten.

Rule 4b. In cases of separate rather than joint possession, use the possessive form for both.