In this case, possessive nouns show ownership or belonging. In other words, if a noun has something that belongs to it, we need to turn that noun into its possessive form.

The possessive case shows the relationship of a noun to other words in a sentence. That relationship can be ownership, possession, occupancy, a personal relationship, or another kind of association..

Note: As our examples above demonstrate, when one of the co-owners is written as a pronoun, you will need to use possessive adjectives (my, your, her, our, their). You will want to avoid possessive pronouns (mine, yours, hers, ours, theirs) in such situations. In cases of separate rather than joint possession, use the possessive form for both.