Apostrophe + s for Possession

In English, we add an apostrophe + "s" to show possession. Have a look on these rules to understand this point.

1.- Add 's to the singular form of the word (even if it ends in -s):
the owner's car , James's hat (James' hat is also acceptable)
For plural, proper nouns that are possessive, use an apostrophe after the 's':
The Eggles' presentation was good. (The Eggles are a husband and wife consultant team)

2.- Add 's to the plural forms that do not end in -s:
the children's game the geese's honking

3.- Add ' to the end of plural nouns that end in -s:
houses' roofs three friends' letters

4.- Add 's to the end of compound words:
my brother-in-law's money

5.- Add 's to the last noun to show joint possession of an object:
Todd and Anne's apartment

Note that we do not use apostrophes with the possessive pronouns hers, its, ours and yours, but we do use them with possessive pronouns that end in "-one" or "-body":
Give the cat its dinner Those books are ours.
It must be somebody’s Everyone’s papers are on the table.

Try these exercises to solve your doubts:
Quizz 1 /quizz 2 / quizz 3 / exercises 1 / exercises 2 / exercises 3 / exercises 4 /exercises 5.