There are three correct ways to use apostrophe in English:
- To indicate omissions (as in contractions, see below)
- To indicate possession
- To clarify typography in certain instances so readers are not confused.
If we want to simplify words and phrases like cannot, will not, should have, it is CORRECT BUT INFORMAL usage to use an apostrophe in a contraction, like this:
- cannot – can’t
- will not- won’t
- should have- should’ve
One use of apostrophe s is to show possession, i.e. who owns/has what or who. An example:
Those are Chloe’s books (in other words, those are the books that belong to Chloe).
Since English is a complicated language that allows for great precision, where we use the apostrophe s is important. If you put it in a different place, you change the meaning of the sentence!
Each of these four phrases has a distinct meaning:
- My sister’s friend’s roller-skates (the roller-skates belonging to a friend of my sister)
- My sister’s friends’ roller-skates (the roller-skates belonging to several friends of my sister)
- My sisters’ friend’s roller-skates (the roller-skates belonging to a friend of several of my sisters)
- My sisters’ friends’ roller-skates (the roller-skates belonging to several friends of several of my sisters)
The writer Kingsley Amis, on being challenged to produce a sentence whose meaning depended on a possessive apostrophe, came up with:
- Those things over there are my husband’s. (Those things over there belong to my husband.)
- Those things over there are my husbands. (I’m married to those men over there.)
Apostrophe “s” to clarify abbreviations and other ambiguous things:
- CD’s- means either more than one CD, or something belonging to the CD (e.g. paper insert). You have to judge from context which one is intended. In an academic paper, since it is a FORMAL writing situation, you would avoid the use CD and actually type out “compact discs”.
- DVD’s- same as for CD’s
- A’s- more than one grade of A, as in Rob got all A’s on his report card. Without the apostrophe, a person couldn’t tell if the word “as” had been typed with a bad capital “A” or not. You use apostrophe “s” for other letter grades, too, such as B’s, C+’s and so on. If you were referring to batteries, you might use it this way, too. Example: “I needs three AA’s for my flashlight”
What not to do . . .
Please DON’T use apostrophe “s” to indicate the plural form of a word that is not an abbreviation.
- Book’s – this means something belonging to the book, not more than one book
- Lady’s- this means something belonging to a lady, not more than one lady
- Cup’s – this means this means something belonging to the cup, not more than one cup