There are two signs near my home that are prime examples of how not to use apostrophes. One offers “Roof’s fixed cheap” and another offers “Worm’s and crawler’s.” I have desperately wanted to go repaint the signs at night so they’d be done correctly.
Here’s the basic rule: Plural words don’t use an apostrophe, possessive words and contractions (combining two words) do. Let’s try some examples:
Incorrect: The cat’s are black. (We’re talking about more than one cat, plural.)
Correct: The cats are black.
Incorrect: The girls skirt is pink. (The skirt belongs to the girl, making it possessive.)
Correct: The girl’s skirt is pink.
Incorrect: The girls skirt’s are pink. (We have more than one girl, with more than one skirt.)
Correct: The girls’ skirts are pink.
The last example has a plural possessive, which is tricky. If there is more than one subject that owns something, the apostrophe goes after the S.
You can try to remember correct apostrophe use by asking yourself some questions. Is it more than one? If so, it’s plural and doesn’t use an apostrophe. Does it own something? If so, use an apostrophe plus S. Is it more than one and it owns something? If so, use an apostrophe after the S.
I also mentioned contractions. When you put two words together you’ll use an apostrophe. For example, I just used “you’ll” which is a contraction of “you will.” Slang contractions can get complicated, but if you know for certain that it’s a combination of two words, like “do not = don’t” be sure to use that apostrophe.
When pluralizing an acronym or number, don’t use an apostrophe. You can have three DVDs (not DVD’s) and be born in the 1970s (not 1970’s). Also, it would be correct to say that your DVDs’ covers are made of paper.
If you’re stuck and don’t know what to do, try writing the sentence out fully. For example, the first sentence above involving the cat could be written “There is more than one black cat.” The final sentence about the girl’s skirts could be written as “There was more than one girl and each had a pink skirt.” You can also write out contractions if you’re not sure where the apostrophe goes, such as “did not” instead of “didn’t.”