“Your vs You’re” may be one of the most common offences with which social media users are often charged by the grammar police. In this Ed’s Elevenses blog post, we will look at the three (and sometimes four) major functions of apostrophes and ways to use them appropriately in writing.
What do apostrophes do?
Some grammar books list as many as eight uses for apostrophes, but there really are only four to worry about:
- To indicate missing letters
- To indicate a possessive/relationship
- To indicate time/quantity
- To indicate a plural
1. To indicate missing letters
“Mary’s very sad because her partner hasn’t won the lottery.”
As we can see from this sentence, apostrophes are used to indicate the letters and spaces that have been removed when one word is created from two.
Here, “Mary’s” is a contraction of “Mary is”, whereas “hasn’t” means “has not”.
An apostrophe is needed when pronouns are abbreviated, for example, it’s (it is), you’re (you are), who’s (who is), and they’re (they are).
These four, in particular, are not to be confused with their apostrophe-less equivalents: its, your, whose, and their/there. The best way to avoid such confusion is to check the meaning:
✅ It’s (= It is) a dog.
❌ Its a dog.
✅ You’re (= You are) happy.
❌ Your happy.
✅ Who’s (= Who is) on the phone?
❌ Whose on the phone?
✅ They’re (= They are) Mary and Peter.
❌ Their Mary and Peter.
❌ There Mary and Peter.
We also use an apostrophe to indicate missing letters at the beginning, middle, and end of a word.
Omission of start-of-word letters is usually used to indicate informal speech or a speaker’s accent:
✅ ’Twas (= It was) the night before Christmas.
✅ Tell ’em (= them) where he’s gone.
✅ ’Tis (= It is) Hallowe’en (= All Hallows Evening). [Note: The abbreviation “Hallowe’en” is a bit old-fashioned.]
Consider why Mary is not happy again, but let’s abbreviate “because” this time:
✅ Mary’s very sad ’cause her partner hasn’t won the lottery.
❌ Mary’s very sad ‘cause her partner hasn’t won the lottery.
When you enter a single quotation mark to indicate omission, double check if it is not an opening single quotation mark (‘). Apostrophes are always the closing single quotation mark (’).
2. To indicate a possessive/relationship
“Mary’s dog’s called Buttons.”
As explained above, “Mary’s dog’s called” is a contraction of “Mary’s dog is called”, but “Mary’s dog” here indicates the possession of Mary’s (i.e., the dog of Mary’s).
Now, let’s look at some complicated issues. The most common problem I see is writers struggling to place the apostrophe correctly when a word ending in S is used in the possessive case.
Consider Mary’s dog, Buttons:
✅ Buttons’s favourite food is watermelon.
✅ Buttons’ favourite food is watermelon.
Both of the above are standard singular-possession usage. However, I personally favour the rule—if a word ends in S, an apostrophe and second S are added to mark the relationship: James’s car, Chris’s cake, Charles’s parents and so on.
Now, consider plural nouns that end with an s, and those that do not.
Given Mary’s family name is “Jones” (i.e., her full name is Mary Jones), let’s talk about her family house:
✅ The Joneses’ house is huge.
❌ The Joneses’s house is huge.
When we talk about a family collectively, we have to pluralise the surname (family name/last name), such as the Williams (Peter William’s family), the Monsoons (Edina Monsoon’s family). For a more detailed guide on making family names ending in an s, x, or z sound plural, read How to Pluralise Surnames.
To make a multiple possession, as when we talk about the house possessed by Mary’s family (i.e., multiple members), we only need to put an apostrophe after the final S when a plural ends in S:
✅ Their neighbours’ dogs.
❌ Their neighbours’s dogs.
For plurals that do not end in an s, we have to add apostrophe+S: children’s toy, women’s clothes, people’s choice.
When there are a set of linked nouns, add apostrophe(+S) after the last one:
✅ Mary and Peter’s dog.
❌ Mary’s and Peter’s dog.
✅ The Joneses and their neighbours’ dogs.
❌ The Joneses and their neighbours’s dogs.
3. To indicate time/quantity
“In two weeks’ time, Buttons will be three months old.”
Apostrophes are used to indicate the specific length of a period of time. Here, the time period (“two weeks”) modifies a noun (“time”), so an apostrophe is required.
Consider how old Buttons will be:
✅ Buttons will turn three months old.
❌ Buttons will turn three months’ old.
Here, the time period (“three months”) modifies and adjective (“old”), therefore, we do not use an apostrophe here. Read When to Use a Hyphen for a more detailed guide on talking about age in writing.
The same goes with other adjectives:
✅ Mary is nine months pregnant.
❌ Mary is nine months’ pregnant.
✅ The Joneses’ house is four storeys high.
❌ The Joneses’ house is four storeys’ high.
4. To indicate a plural
“Buttons ate a few CDs that Mary bought in the 90s.”
Here, “CDs” indicates the plural of CD while “90s” indicate plural numbers (i.e., the years 1990–1999).
No apostrophes are needed for plural numbers or upper-case abbreviations:
✅ Their neighbours are CEOs.
❌ Their neighbours are CEO’s.
However, it is essential to use an apostrophe when indicating the plural of lower-case letters:
✅ There are two t’s in Buttons.
❌ There are two ts in Buttons.
✅ Delete all the and’s in this paragraph.
❌ Delete all the ands in this paragraph.
Summing up
The most helpful advice when dealing with apostrophes is to always do a quick check of the meaning.
1. Omission: When two (or more) words become one, add apostrophe:
✅ I’ve (= I have) had lunch.
✅ ’Tis (= It is) a fun game.
❌ ‘Tis a fun game. (Never use an opening single quotation mark)
2.1 Possession/Relationship: add apostrophe+S after a singular noun:
✅ My friend’s website.
✅ James’s bag.
2.2.1 Possession/Relationship: add apostrophe after a plural noun that ends with S:
✅ My cats’ box.
2.2.2 Possession/Relationship: add apostrophe+S after a plural noun that does not end with S:
✅ My children’s books.
3. Time/Quantity: add apostrophe(+S) when the time modifies the noun:
✅ They are celebrating their ten years’ anniversary.
❌ The castle is 800 years’ old. (“Old” is an adjective)
4. Plurals: add apostrophe+S after the lower-case plural:
✅ The two i’s in skiing.
❌ The two is in skiing.
✅ We are the DJs.
❌ We are the DJ’s. (“DJ” is an upper-case abbreviation)
✅ The music is from the 80s.
❌ The music is from the 80’s. (“80s” is a plural number)
Edison Tam MA MCIL CL is a Translator, Proofreader, and Copyeditor (zh-hk/en) who works with students, independent non-fiction writers, academic researchers, and clients from businesses and organisations of all sizes.
He is Chartered Linguist and Member of the Chartered Institute of Linguists (CIOL), and has undergone wide-ranging academic training in Business, Modern Languages, and Applied Linguistics in Hong Kong, London, and Barcelona.
The Languaging Lab | 香港翻譯校對服務 