1. Apostrophes

2. Apostrophes with Possessives
For singular nouns use ‘s
the book’s author; the flower’s smell
For singular noun that ends in s, the added s after the apostrophe is optional
James’s car (or) James’ car
For plural nouns ending in s, add only an apostrophe
both teams’ colors; six days’ vacation

3. Apostrophes with Possessives
For plural nouns not ending in s, use ‘s
the children’s game; four men’s cars
For the indefinite pronoun (pronouns ending in –body and –one), use ‘s
no one’s fault; somebody’s hat
For compound words, add ‘s to the last word
brother-in-law’s house; everyone else’s water

4. Apostrophes with Possessives
For joint ownership by two or more nouns, add ‘s after the last noun
Mary and Tim’s house; bar and grill’s parking
For individual ownership when two or more nouns are used, add ‘s after each
Mary’s and Tim’s houses;
Mine and Tim’s house; Tim’s and my houses (never write or say I’s)

5. Apostrophes with Contractions
Use the apostrophe to mark omitted letters or numbers
it’s = it is (its shows possession)
who’s = who is (whose shows possession)
’79 = 1979
what’ve = what have

6. Apostrophes with Plurals
Use apostrophes to form plurals of lowercase letters and abbrevations with periods. Always use ‘ with A or a.
k’s B.A.’s A’s a’s
The apostrophe is optional for numbers, abbreviations without periods, and symbols
UFOs or UFO’s
1950s or 1950’s (I prefer ’50s over ’50’s)
do’s and don’ts
#s or #’s; &s or &’s

7. Unnecessary Apostrophes
Don’t use the apostrophe with possessive pronouns.
his, hers, its, ours, yours, theirs, whose
Don’t use the apostrophe with regular forms of plural nouns that don’t show possession.
two cars, but the car’s driver
The Smiths went to three parades.