One of the quirkiest, some might say dumbest, parts of the English language is making words possessive.
The main henchman for carrying out this task is the humble apostrophe.
How exactly the apostrophe is used to show ownership is complicated, and we’ll get to that. First though, let’s look at some other uses of this floating comma.
Omitted letters or numbers
Use the apostrophe to indicate when letters have been left out (for instance, in contractions like “isn’t” or “I’ve”) or when numbers have been dropped (as in, “the summer of ’69,” or “the roaring ‘20s.’”)
Single letter plurals
If you need to make one letter plural, add an apostrophe, as in “straight A’s.” However, don’t use this same process for numbers: Just add an s, as in, “he gave me my change in $1s.”
For quotes within quotes
If you’re quoting someone who’s quoting someone, use a single quote — aka, an apostrophe — within the quotation marks, as in: “Right before she dumped me, she said, ‘you’ve been playing video games for the last 19 hours.’”
With those minor uses out of the way, let’s tackle the gnarly mess that is possessives.
Let’s start easy and ramp it up.
To make a word possessive that does not end in “s,” you generally simply add an apostrophe and an “s,” even if the word is already possessive. So for instance: elephant’s toes, deer’s antlers, men’s socks.
If you’re using a joint phrase, such as “the elephant and the deer’s toes,” only the second noun gets the possessive, not the first.
Now’s where things get a little complicated and hard to remember.
If you have a proper noun that ends in “s,” just add an apostrophe to make it plural: Carlos’ piano, the Smiths’ house, Arkansas’ capital.
But, just to keep things spicy, if it’s a common (non-capitalized) noun ending in “s,” you add an apostrophe and another “s”: dress’s zipper, iris’s petals, crisis’s conclusion.
Note: this is an updated rule. In previous versions of AP style, you added only an apostrophe if the next word started with an “s” as well. It’s a small mercy that we no longer have to remember that.
But of course, there are still exceptions.
AP style says to not add an “s” to the phrases “for appearance’ sake,” “for conscience’ sake” and “for goodness’ sake.” But this only applies in these specific constructions — any other plural possessive form of these words call for an apostrophe “s.”
This is a good time to remind you that you don’t have to follow all of AP style rules. As long as you’re consistent, feel free to craft your own exceptions — or choose to ignore certain aspects of AP style altogether if they’re cumbersome or don’t fit your needs. Just make sure you’re keeping everything up to date in your in-house style guide.
Yes, these rules can be complex and hard to remember. But keep your style guide handy, make yourself a cheat sheet on a Post-It and just focus on being internally consistent.