Persons', is that correct? Should it not be person's?
The apostrophe has four functions.
Possession
Plural
Contraction
Direct speech/quotes
I will explain each function below with examples.
Possession
Who owns what? The apostrophe is used to show who has, owns, or controls something. The tricky part is choosing whether to use an apostrophe only or to use 's instead.
Use 's after a
Singular noun – e.g., donkey
Plural nouns that don't end with 's' – e.g., people
Indefinite pronouns – e.g., anyone
Use an apostrophe only after a plural noun that ends with 's'.
Example:
'Whose laptop is that?'
'Oh, it's my mothers' laptop.'
Mothers' or Mother's?
Both can be correct.
Mothers is a plural noun ending with s. So if you have two mothers, and they share a laptop, you put the apostrophe behind the s – mothers'.
Does the laptop belong to one mother, and it doesn't matter if you have one or two, then you add 's – mother's.
Always double-check where you put the apostrophe because the meaning of your text depends on it.
Plural
ONLY ever use 's to express plural letters or symbols if it is necessary for clarity.
For example,
How many i's was that?
They only sold those doughnuts in packs of 2's or 4's.
You used too many 6's in this document.
Don't fall into the greengrocer's apostrophe trap! AKA using 's to show a plural noun – e.g., potatoes vs potato's.
Contraction
You will often find the apostrophe in colloquial language. The apostrophe shows the reader that a letter is omitted.
For example,
Can't vs Cannot
T'other vs The other
Y'all vs You all
That's vs That is
'twas vs It was
Nothin' vs Nothing
Direct speech/quotes
Have you ever made those double quotation marks with your fingers when trying to "express" something? Well, this is exactly what the apostrophe does. It shows the reader that the narrator is no longer talking, instead, we "hear" how a character, interviewee, specialist, etc. express themselves in their own words.
In the UK*, we use the apostrophe for direct speech and quotations in writing. When there is a quote within a quote, you use double quotation marks to differentiate the two.
Millie said, 'You won't believe what I heard. Fidget literally said, "I like sprouts." Can you believe that?'
In the US*, it is the other way around. US-style writers use double quotation marks for direct speech and quotations and use the apostrophe for in-speech quotes.
Millie said, "You won't believe what I heard. Fidget literally said, 'I like sprouts.' Can you believe that?"
Thank you for reading.
Please note that there are more apostrophe guidelines for some of these functions. However, the rules in this post are sufficient for most texts.
Which apostrophe function is your Achilles heal?
Possession
Plural
Contraction
Direct speech/quotes
If you want to go more in-depth on apostrophes, you can read p.69–75; 162–165 from New Hart's Rules (UK) or p.408; 422–427 from The Chicago Manual of Style (US). You can find both books here.
*There are no set rules for using single or double quotation marks. These are UK/US preferences, not a rule. Always follow your own style sheet or style guide.