An apostrophe is used to show that a person or object belongs or relates to someone or something.
Instead of saying “the mother of Sally” or “the rays of the Sun” we simply say Sally’s mother or the Sun’s rays.
With singular nouns and most personal names add an apostrophe plus -s
The party was at Pete’s house.
The dog’s bowl was empty.
Mum’s car broke down on the way home from town.
Last Friday’s concert was excellent.
With personal names that end in -s, if you would naturally pronounce an extra -s when you say the name out loud, then add an apostrophe plus an -s :
The nurse worked at St. James’s hospital in Leeds.
Charles’s brother is a professional footballer.
With personal names that end in s but with which you would not pronounce the extra -s, just add an apostrophe after the final -s :
A Christmas Carol was the shortest of Dickens’ novels.
Wesley Snipes’ best film was probably Demolition Man.
With plural nouns ending in -s, add an apostrophe after the final -s :
Edward borrowed his parents’ car.
Just inside the door was the ladies’ cloakroom.
Footballers’ wives sit together to watch the game.
With plural nouns that do not end in -s, add an apostrophe plus an -s:
The men’s cloakroom was at the end of the corridor.
The children’s centre is closed on Saturdays.
Top Shop sells women’s clothing.
Note: possessive pronouns/determiners do not need an apostrophe to denote possession ( his, hers, ours, yours, theirs)