1. Avoid an apostrophe catastrophe
Possessives and apostrophes

2. When to Use an apostrophe

3. Use an apostrophe with a noun to indicate ownership or possession of something.
A noun showing ownership usually comes just before the name of whatever is possessed. If you are unsure whether possession is being shown, use the “of” test:
Bird’s nest=the nest OF the bird
Clown’s nose=the nose OF the clown
Men’s suits=the suits OF the men

4. Add an ’s to singular nouns
The baby’s toys are on the floor. (the toys of one baby)
The town’s holiday festival is tomorrow. (the festival of one town)
The worker’s salary is low. (the salary of one worker)
Add only an apostrophe to plural nouns that end in s
The babies’ toys are on the floor. (the toys of several babies)
The towns’ holiday festivals are tomorrow. (the festivals of several towns)
The workers’ salaries are low. (the salaries of many workers)

5. Add ’s to plural nouns not ending in s
Children’s movies can be entertaining.
The men’s department is upstairs.
Add ’s to the last word in compound words
My brother-in-law’s business is about to fail.
It’s usually somebody else’s fault.

6. Add ’s to the last noun to show joint possession
Joe and Janet’s house is up for sale. (They both own the house.)
Add ’s to each noun to show individual (separate) possession
Joe’s and Janet’s cars are similar. (Each person has a car.)

7. Use an apostrophe to form contractions
Use an apostrophe to form contractions. A contraction replaces one or more letters, numbers, or words.
It’s=it is
They’re=they are
Can’t=cannot
Everyone’s=everyone is
Class of ‘08=class of 2008

8. Use an apostrophe to form the plural of lower case letters.
Ed’s i’s look like e’s.
The apostrophe is optional to mark plural abbreviations, dates, and words used as words. However, most current style guides recommend leaving out the apostrophe.
CD’s or CDs
2000’s or 2000s
9’s or 9s
maybe’s or maybes

9. When not to use an apostrophe

10. Do not use an apostrophe to form the plural of a noun.
NO: There are several swing set’s for sale.
YES: There are several swing sets for sale.
NO: We are keeping up with the Jones’s.
YES: We are keeping up with the Joneses.
NO: The menu includes fish taco’s.
YES: The menu includes fish tacos.
Do not use an apostrophe with verbs ending in s.
NO: Kelly swim’s very well.
YES: Kelly swims very well.

11. Do not use an apostrophe with possessive pronouns.
NO: The house is all your’s.
YES: The house is all yours.
NO: The purse is her’s.
YES: The purse is hers.
NO: The crocodile snapped it’s jaws.
YES: The crocodile snapped its jaws.

12. Do not use an ’s to form the possessive of plural nouns.
NO: We washed the Smith’s car.
YES: We washed the Smiths’ car.
NO: I called both the boy’s mothers.
YES: I called both the boys’ mothers.

13. Apostrophe abuse