Nouns that show ownership are called possessive nouns.

To form the possessive of a singular noun, add an apostrophe and an s (-'s).

To form the possessive of a plural noun, only add an apostrophe if the word ends in s.(-s')

If the plural of the noun does not end in s, add an apostrophe and an s (-'s).

Examples: Tom’s bell, the authors' books, men’s race