POSSESSIVE NOUNS

     Possessive nouns are those nouns that show possession. Possessive Nouns are used to show ownership. A noun is possessive only when a phrase can be modified to say that an idea or commodity belongs to something or someone.

General Rules

RULE ONE: Most words simply get apostrophe S ('s).

the box belonging to Steve -> Steve's box 

the bedroom of the child -> the child's bedroom 

RULE TWO: Plural nouns ending in S simply get an apostrophe (s'). 

the box belonging to the girls -> the girls' box
the bedroom of the kids -> the kids' bedroom 

RULE THREE: For irregular plurals (not ending in S), add apostrophe S ('s).
the coats of the women -> the women's coats
the jackets of the children -> the children's jackets 

RULE FOUR: For names ending in S, add apostrophe S ('s).
the cat belonging to Charles -> Charles's cat
the jacket of the Phyllis -> Phyllis's jackets 

ALTERNATE RULE FOUR: For names ending in S, simply add an apostrophe (s').
the cat belonging to Charles -> Charles' cat
the jacket of the Phyllis -> Phyllis' jackets