A singular possessive noun shows ownership by one person or thing.
We add an apostrophe (') and s to most singular nouns to show possession.
Jerome's pet dog barely barks.
My teacher's desk is always neat and tidy.
The cat's whiskers are really long.
A plural possessive noun shows ownership by more than one person or thing.
To form the possessive of a plural noun ending in s or es, add only an apostrophe (').
To form the possessive of a plural noun that does not end in s, add an apostrophe and s ('s).
The birds' nest had many eggs.
The foxes' lair was hidden under the ground.
The men's beards were really thick and long.