Possessive nouns and pronouns possess.
It’s (yes, it is) that simple, but here’s (here is) the catch:
Those possessive little nouns need an apostrophe and then an “s” to show ownership or possession – for example: Sarah's computer, Jonathan's car, Marjory’s necktie. (She can have one if she wants!)
When it comes to pronouns, though, an apostrophe “s” won’t (will not) do! The word itself changes: Her desk instead of She’s desk, or His remote control instead of He’s, or Their bowl of popcorn instead of They’re bowl, and Its wings, not It is (It's) wings, which brings us back to contractions:
It’s = It is.
They’re = They are.
He’s = He is.
She’s = She is.
But what if you want to contract a noun with a verb? Don’t! (As in, do not have a noun in a contraction.) Jane’s desk is hers, but it’s (it is) not her, so Jane’s book cannot mean Jane is book. It’s (it is) her book.
Got it? Think about it. Read all about it, and you will.
© 2014, Mary Harwell Sayler, poet-author of 26 books for Christian and educational markets, including two books of poetry, Living in the Nature Poem and Outside Eden