Grammar Apostrophes for Singular and Plural Possession

Apostrophes can show possession (belonging).

In most singular nouns the apostrophe should go before the 's'.

The cat's tail

In most plural nouns ending in 's' the apostrophe should go after the 's'.

The cats' tails

In most plural nouns not ending in 's' the apostrophe should go before the 's'.

The women's tournament