Punctuation Means Something, You Know!
Look at the difference between these two sentences:
Your dog died.
Your dog died?
They mean something very different. Why? Punctuation.
For some reason, however, people use apostrophes in all the wrong places. That's like mixing up ? and . It makes both marks meaningless, and then people won't know what you mean.
Apostrophes Are Used For Possession
The dog's nose
John's book
America's century
Add 's after a word to make it possessive, or, in other words, to show that word is the owner of the one after it. If you can turn "the x's y" around to mean, "the y of x," then the apostrophe belongs there.
If a word ends in an s already, then you add the ' after the s.
So, if you're selling t-shirts, you can talk about t-shirts' sizes. If your talking about keeping up with the Joneses, then you may want to sneak a peek at the Joneses' new car.
What if you've got two people who own something?
Remember Bill and Ted's Excellent Adventure?
They both had the same adventure, so add 's to the last person in the list.
But if EACH of them owns things SEPARATELY, then each of them gets their own 's. What?
Look.
Bill's and Ted's noses are big.
Each has his own nose; they don't share the same nose.
Apostrophes Also Show Contraction: Two Words Squashed Together
It is gets squashed (contracted) to it's.
They are gets contracted to they're.
NOTE:
Hi is one word. It's not a contraction of two words! It's just a pronoun meaning "belonging to him." Since it's not a contraction, no letters have dropped out, and you don't need an apostrophe.
In the same way, its -- meaning "belonging to it" -- is not a contraction of anything. It's a pronoun. The cat's tail, its tail.
See? So his, hers, its, their, your and our never need an apostrophe, because you can't break them apart into two words, the way you can it's --> it is, they're --> they are, you're --> you are, we're --> we are.
Plural Nouns do NOT use an Apostrophe
In the same way, CATS are just CATS. Two cats? Cats.
Five horses? Horses.
NO APOSTROPHE.
Why?
Because apostrophes mean one of TWO things:
1. ownership/possession: "X of the Y" (e.g. The cat's tail, the horses' field)
2. two words squished together, with an apostrophe showing the joint and the place where letters might have been dropped: "Bob's your uncle!" means "Bob is your uncle."
Remember those two things, and you'll never confuse its with it's again!
