The possessive case of most singular nouns, whether common or proper, is formed by adding – ’s to the end. See the following examples: This is Mary and her dog. The dog is Mary’s pet; Mary is not the dog’s pet. This thick curtain is capable of shutting out the summer sun’s heat and light.

We use possessive pronouns in place of a noun: Is that [determiner] your scarf? It’s very similar to [pronoun] mine. (It’s very similar to my scarf.) That’s not [determiner] their house. [pronoun] Theirs has got a red front door. It was [determiner] his fault not [pronoun] hers.

We add 's to singular nouns to show possession: We are having a party at John's house. Michael drove his friend's car. We add ' to plural nouns ending in -s: This is my parents' house. Those are ladies' shoes.