Apostrophes in English are used for possession and contraction. They are not used to form plurals.
POSSESSION :
Apostrophes are used to indicate possession in nouns (but not in pronouns: hers, ours, theirs….).
- The girl‘s bicycle.
- The bicycle is hers (not her’s).
To show possession, ‘s is added to a singular noun (even if the noun ends in ‘s’).
- John‘s car.
- James‘s guitar.
To show possession in a plural noun, the apostrophe is added after the plural s.
- My parents’ house is near the coast.
- Visitors are not allowed into the students’ rooms.
- Witches’ hats are pointed.
If the word is plural but does not end in s, simply add an ‘s for possession.
- The children’s playground is beside the school.
CONTRACTION :
Apostrophes are used to indicate missing letters in contractions. For example:
- He’s is a contracted form of he is.
- It’s is a contracted form of it is.
- Its is a possessive pronoun like ‘my’, ‘his’, ‘her’, etc.
- The dog was chewing its toy.
It’s (it is) its toy so that’s (that is) ok. - Who’s is a contracted form of who is.
- Who’s (who is) the owner of the red car?
- Whose car was damaged during the storm?
