Rules for Apostrophes that Show Possession

To show possession of a singular noun, simply place an apostrophe and an -s to the end of the word:

Tyrone‘s bicycle, the pencil‘s eraser, the dog‘s collar

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To show possession of a plural noun that already ends with an -s, simply place an apostrophe at the end of the word:

four cats‘ litter boxes, two babies‘ cribs, three teachers‘ gradebooks

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To show possession of a plural noun that does not end with an -s, simply place an apostrophe and an -s at the end of the word:

two women‘s notebooks, four children‘s crayons, three geese‘s feathers

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Rules for Apostrophes to Indicate Missing Letters

An apostrophe is used to indicate the placement of missing letters in a contracted word:

cannot > can‘t

do not > don‘t

I will > I‘ll

is not > isn‘t