Apostrophe:

When we talk about the possession of singular nouns so we use ('s)

• Aliya's house is a big.
• This is my friend's book.
• Naila's suits are in the almari.
• Child's cap is here.
• Today is charles's birthday.
• That woman's watch is very expenssive.
• Boy's book is on the table.

When we talk about the possession of regular plural nouns so we use (')

• Boys' classes are there.
• My friends' houses are in my street.
• Girls' books are in the shelf.
• Captains' helmets are green.

When we talk about the possession of irregular plural nouns so we use ('s)

• I like women's universities.
• Children's toys are broken.
• Men's shoes are at this shop.

When we talk about two names before singular nouns so we use ('s) with 2nd name.

• Raman and Ajaz's house is in this street.

When we talk about two names before plural nouns so we use ('s) with 1st and 2nd names.

• Anwar's and Ahmad's houses are on the 1st street.