Apostrophes

Today's topic: The apostrophe

This little guy tends to be a bit overworked these days, as in the following sentence: 

All student's must register for the workshop by October 16.

Can you spot the mistake?  The word "students" should not contain an apostrophe. 
Why not?  Let's examine the purpose and proper use of this little tadpole-like punctuation mark.

Apostrophes have two uses:

1.) To indicate ownership/possession, as in:

That is Sarah's car.

That guy ate all the kids' desserts!  (Note: In this sentence, the noun is plural--kids--so the  apostrophe goes after the s.  In the first sentence, "Sarah" is singular, so the apostrophe goes before the s.)

2.) To replace the missing letter or letters in a contraction, as in:

That's my notebook.  (The apostrophe helps us turn the phrase "that is" into the contraction that's.)

Oh no, it's raining.  (The phrase "it is" becomes "it's.")

I should take this opportunity to point out that the ONLY TIME an apostrophe is okay in the word "it's" is when you mean to say "it is."  Never use it like this: "The panda cuddled it's cub."  This is correct: "The panda cuddled its cub."

Apostrophes should not be used to form a plural noun.  

INCORRECT: I love cat's. (Your reader might wonder, "You love Cat's what?  Cat's blue sweater?  Cat's new house?")
CORRECT:  I love cats.

INCORRECT:  All participant's signed a waiver form. 
CORRECT:  All participants signed a waiver form.

INCORRECT:  Could you get us some soda's?
CORRECT:  Could you get us some sodas?

INCORRECT:  I saw twelve patient's today. 
CORRECT:  I saw twelve patients today.

There are (of course) a few little tricky situations in which these rules might not be so clear-cut--for example, how do you indicate possession with a noun that ends in s?  Is it Mr. Jones's car, or Mr. Jones'?  For the answer to that and several more tricky apostrophe questions, click here for "Grammar Girl" Mignon Fogerty's apostrophe tutorial:  http://grammar.quickanddirtytips.com/apostrophe-plural-grammar-rules.aspx

I hope you found this post useful.  Have a great day!

Whitney Kurtz-Ogilvie, MFAW