Apostrophe Rules. Tip#3: Apostrophes and Possessive Nouns
The rules about forming possessives probably cause the most apostrophe confusion. They vary a little bit, depending on what type of noun you are making into a possessive. Here are the rules of thumb:
For most singular nouns, add apostrophe+s:
Example: The dog’s leash; The writer’s desk; The planet’s atmosphere.
For most plural nouns, add only an apostrophe:
Example: The dogs’ leashes (multiple dogs); The writers’ desks (multiple writers); The planets’ atmospheres (multiple planets).
For plural nouns that do not end in s, add apostrophe+s:
Example: The children’s toys; The geese’s migration route.
