Apostrophes are one of the more confounding punctuation marks. If you search for signs with “grammar errors” online, most of the results will likely include an apostrophe error (which is actually a punctuation error, not a grammar error, but I digress). Here are some of the most common ways to use apostrophes—and some interesting rare cases.
1. For Possessive Nouns
When you consider apostrophes, the first word that probably comes to mind is possessive because our grade-school teachers taught us that apostrophes make things possessive—more specifically, apostrophes make nouns possessive. We use apostrophes to write about Oprah’s new recommendation, J.K. Rowling’s new book, and Taylor Swift’s new song.
2. For Compound Possession
When you’re writing about the possessions of two people, it’s a little different. Before you can place your apostrophes, you need to figure out whether the people have the thing together or separately:
- If they possess the thing together, use one apostrophe on the final name: Frannie and Luke’s house is at the end of the street.
- If they have separate possessions, each person needs an apostrophe: Frannie’s and Luke’s bikes are in the garage.
- If you’re mixing nouns and pronouns, they both need to be possessive no matter who owns what: Frannie’s and my house is at the end of the street. (Although such sentences are correct, they often sound awkward. It’s usually better to reword them to something like Our house is at the end of the block, or The house where Frannie and I live is at the end of the block.)
3. NOT for Possessive Pronouns
Not all apostrophes are for possessives though. You don’t use apostrophes to a make pronouns possessive, for example. Instead, pronouns have their own possessive forms that have different spellings. You’re, it’s, and they’re are not possessive pronouns; they are contractions of you are, it is or it has, and they are. Instead, to become possessive, the pronoun you becomes your, it becomes its, and they becomes their.
4. For Contractions and Other Omissions
Apostrophes in contractions such as it’s and they’re show that letters have been omitted. Other examples of contractions with omitted letters include can’t, he’d, and o’clock. Although the more opens in a new windowobscure contractions such as I’d’ve, there’re, and that’ve are properly formed because the apostrophes mark the omitted letters, it’s best to avoid them because they distract readers. (If you read very old manuscripts, you’ll see all kinds of strange contractions and words with two apostrophes. They were more common in the past before spelling became as standardized as it is today.)
5. For Years with Omitted Numbers
If you omit the first two numbers of a year, you should also indicate the omission with an apostrophe (e.g, the ‘60s). But be careful. Many word processors will insert a single open quotation mark at the beginning of a word instead of an apostrophe, but these marks aren’t interchangeable because they face opposite directions. Often the easiest way to get an apostrophe is to copy and paste one from a different spot in your manuscript.
6. For Rare Plurals
It used to be more common to use apostrophes to make abbreviations plural (e.g., CD’s). The New York Times was the last major publication to drop this style, and the nearly universal style today is to simply add an S (e.g., CDs).
The same is true of numbers. It used to be common to use an apostrophe to make years plural (e.g., 1960’s), but today, the common advice is to simply add an S (e.g., 1960s).
Apostrophes are still often used to make single letters plural, however. You tell people to opens in a new windowmind their P’s and Q’s, dot their I’s, and cross their T’s, and you turn on the TV to watch the Oakland A’s. Letter grades are an exception though: They are usually capitalized and written without an apostrophe (e.g., I got three As and two Bs.).
7. For the Past Tense and Participles of Rare Verbs
Occasionally, verbs are formed from all capital letters, and in those instances, it is acceptable to use an apostrophe to form the past tense and to form the participle. For example, the Chicago Manual of Style recommends using OD’d for the past tense of the verb to overdose when it is abbreviated OD, and the Associated Press recommends using OK’d for the past tense and OK’ing for the participle of the verb to OK.
Industries often have jargon that you wouldn’t use when communicating with the public, but you can use when communicating internally. If your industry uses such abbreviations as verbs, it may be fine to use an apostrophe to make the past tense and participle (e.g., Have you MAC’d that widget? Gwen is MAC’ing it now.). Check to see if your company has a style guide that recommends how to form such verbs, and if not, check to see how other people in your industry write them.
8. For Some Holiday Names (but Not Others)
Holidays always cause apostrophe confusion because they all have official names but they don’t use apostrophes consistently. In the US, we celebrate Mother’s Day and April Fools’ Day, which have apostrophes, and opens in a new windowVeterans Day, which doesn't have an apostrophe. The names don’t follow a single rule; you have to look up the official spelling for each holiday.
9. For Certain Set Phrases
Finally, some set phrases use apostrophes in ways that aren’t immediately obvious:
Phrases about time and money often take apostrophes: opens in a new windowtwo weeks’ notice and money’s worth.
Phrases that end with sake take a lone apostrophe if they end with an S sound but take an apostrophe plus an S otherwise: For example, for goodness’ sake and for appearances’ sake have an apostrophe at the end of goodness and appearances because those words end with an S sound; but for heaven’s sake and your father’s sake have an apostrophe and S at the end of heaven and father because those words don’t end with S, so they need one.
Addition: A reader named Martin H. wrote in about this additional way to use apostrophes:
"Another use I have seen is to represent a glottal stop or to otherwise aid in the pronunciation of transliterated foreign words. Consider the Jewish holiday of Tisha b'Av, the Israeli artist Ze'ev Raban, the Israeli city of Ra'anana, the spice za'atar, or the toast to life, l'chaim."
A version of this article originally appeared in Office Pro magazine.
Image courtesy of opens in a new windowShutterstock.