Apostrophes have two uses: to indicate a contraction and to show possession.
In contractions, use an apostrophe in place of the letter or letters that are missing.
- Do not = don't
- He will = he'll
To show possession, use an apostrophe and "s" after a singular noun.
Caroline's pet mongoose ran loose all over campus.
The teenager's car had leopard upholstery.
To show possession when a plural noun ends in an "s," put the apostrophe after the "s."
The dogs' collars matched their leashes.
Don't use apostrophes to make a family name (or any other word) plural:
The Goldsteins arrived late to their family-therapy session and found the Briggses had been given their time slot.
However, do use an apostrophe to show possession for plural family names:
The Joneses' appointment had to be rescheduled.
To make plurals of letters, numbers, and abbreviations, some writers add an "s' and some add an apostrophe and "s." Be consistent.
CODs, IOUs, the early 1920s, Ns, Bs, Ph.D.s, 1930's
Here are some exceptions that often lead to errors:
- Don't confuse "whose" and "who's"
"who's" is a contraction for "who is"
Who's missing his underwear?
"whose" refers to possession
Whose underwear is this?
- Don't confuse "it's" and "its"
"It's" is a contraction for "it Is.
It's always a good idea to wear matching socks.
"Its" is the possessive form of "It."
Although the peach was gigantic, its pit was rather small.
Hint #1: Whenever you see an apostrophe with "its," read the apostrophe as an "i." So, if the sentence reads, "Although the peach was gigantic, it's pit was rather small," you could try reading "it's" as "it is" and see if the sentence makes sense. It doesn't, so you know that the apostrophe is incorrect.
Hint #2: Learn the difference between "It's" and "its." This error drives professors crazy.
- A plural noun that does not end in "s" needs an apostrophe and "s" to form the possessive.
The recent campaign focused on women's issues.
Click here to read more about apostrophes in the context of correct grammar.