The possesive case
A noun is in the Possessive or Genitive Case when it is used to show ownership or possession.
It is usually created by adding an apostrophe (') and an -s ending to the noun.
If you want to express the possession in singular, add the apostrophe to the noun before the -s ('s).
the boy's ball
If you want to express the possession in plural, add the apostrophe to the noun after the -s (s').
the boys' ball
The possessive can be also expressed using the of-phrase, particularly when the possessor is not a person.
the leg of the table, the base of the statue.
usually used for people usually used for things