The apostrophe indicates that a letter is missing
As in, that’s, can’t, who’s (who is), there’s (there is), could’ve, fish ‘n’ chips…
One school of thought claims that all apostrophes indicate missing letters, and this alone should inform our use of them.
I agree. Although some instances might require more clarification.
“What about possessives?” I hear you protest (those of you who are still awake).
Merriam-Webster puts it this way…
The ‘s’ at the end of a word indicating possession (“The king’s fashion sense”) probably comes from the Old English custom of adding ‘-es’ to singular genitive masculine nouns (in modern English, “The kinges fashion sense”). In this theory, the apostrophe stands in for the missing ‘e’.
This may not occur to us in the course of our everyday writing, but there are situations when applying the “missing letter” theory might come in useful.
Consider his, hers, theirs, whose and its.
There are no apostrophes in any of those – maybe because they didn’t start off as hises, herses or itses.
The Grocers’ Apostrophe
NEVER insert an apostrophe before an ‘s’ added to make a word plural.
This is known as a grocer’s apostrophe because of its frequent appearance on the signage of grocer’s displays (as in, apple’s and orange’s half price).
(I hope you spotted my deliberate mistake up there at the start. Just checking…)
That’s the straightforward bit.
Nouns ending in s
Some common nouns end in the letter ‘s’ (lens, cactus, bus…), as do many proper nouns (Mr Jennings, James, Christmas). Opinions differ about how apostrophes should be used with such nouns.
There is no right answer, but you should be consistent in whichever guideline you follow.
- Some writers and editors add only the apostrophe to any noun ending in ‘s’ (the lens’ cover, Mr Jennings’ book or James’ car).
- Others add an additional ‘s’ to all such nouns (the lens’s cover, Mr Jennings’s book, James’s car).
- Another method (often used by newspapers and journals) is to add an apostrophe plus an additional ‘s’ to common nouns (as in the class’s homework), but only an apostrophe to proper nouns (Jennings’ book or James’ car). Please note, a book belonging to Mr. Jennings should never be written as Mr. Jenning’s book. His name is not Mr. Jenning.
- The technique I find most consistent with the “missing letter” theory, is to write the word as we would speak it. Most people saying “Mr Jennings’ book” would not pronounce it as “Mr Jenningses book”, so this would be written Jennings’ with no added ‘s’. However, most people would pronounce an added ‘s’ in “James’s car”, so this would be written as it is said: James’s.
This last method is consistent with the usual punctuation of, for instance, for goodness’ sake, but people pronounce things differently too, so nothing’s foolproof. Whichever option you choose, stick to it throughout that letter, story, novel, series… Consistency is a mark of professionalism.
An exception to the rule
There’s always one, isn’t there?
The plural form of individual letters are written with an apostrophe to prevent misreading, so that…
Dot your is and cross your ts becomes Dot your i’s and cross your t’s.
You may never need the two points that follow.
Feel free to stop reading if you’re confused enough already.
Or save them until you do.
Purals of proper nouns
If we refer to the Jennings family as “the Jennings”, that would refer to a family named Jenning. When someone’s name ends in ‘s’, we should add –es for the plural. The plural of Jennings is Jenningses, the members of the Jones family are the Joneses and the two Jameses in the class… well, you get the idea.
To show possession in such cases, add an apostrophe after.
Don’t write the Jennings’ dog, but the Jenningses’ dog.
More than one owner?
This gets more complicated… but it doesn’t crop up often. If you’re talking about separate rather than joint possession, use the possessive form for both.
When they own a car eachJohn’s and Mabel’s cars are both new ;
when the cars belong to both of them, John and Mabel’s cars are both new .
As always, I started out to make a single point and discovered more along the way.
Particularly helpful was the page at https://www.grammarbook.com/punctuation/apostro.asp for usage and examples.
In the unlikely event that you’d like to know more about the history of apostrophes, I recommend http://wmjasco.blogspot.com/2011/08/possessive-apostrophe-his-origin.html as a good place to start.