Fun With Words 3: It's...

The word "it's" has an apostrophe in it, as you've no doubt noticed by now. Hence it's a contraction, AKA "another one of those 'substitution' words that the English language is so annoyingly full of." Ergo, substitute "it is" for "it's" and see if it works:

It's raining cats and dogs.
It is raining cats and dogs, and nobody knows why.

Some more uses of "it's":

It's unusual to find a naked sumo wrestler in your bathtub.
I'm not sure if that's an alien, or if it's Murgatroyd in her bathing suit.
We're celebrating because it's my un-birthday.

Now, "its" is a bit trickier to define. (Don't you hate that?) Basically, it's used to refer to something which belongs to the subject of the sentence, if the subject isn't referred to by "he" or "she". Confusing? Perhaps some examples will help:

IT LOOKS RIGHT, BUT IT'S WRONG:

This taxi has lost it's brakes.

IT LOOKS FUNNY, BUT IT'S RIGHT:

This taxi has lost its brakes.

Or, just try the substitution test as before, and see if "it is" does not work.

The severed head bounced its merry way across the carpet.

"Bounced it is merry way" doesn't work. Ergo, "its", not "it's".

Again, this can seem pretty confusing at first. Check the following examples, and remember contraction (it is) vs. possessive (belonging to something):

This car is defective; it's full of weasels. (Contraction: It is full.)
This car is defective; its engine is full of weasels. (Possessive: the engine, which belongs to the car, is full.)
You've created a monster, and it's running amok. (Contraction.)
You've created a monster; its brain has short-circuited, and it's running amok. (Possessive first, contraction second.)

More examples:

This book has had its spine cruelly broken.
It's too bad the men in the white coats finally caught you.
The moaning mummy lurched its way across the dance floor.

There may be times when to refer to your subject as a he, a she, or an it. (This situation often arises on blind dates.) So, try it both ways and see what works:

The Jabberwock bared its glistening fangs.
The Jabberwock bared his glistening fangs and demanded a Dr. Pepper.

The first might be appropriate if you're portraying the Jabberwock as a mere object for the hero to slay. The second would be better if you're a sympathetic sort, and are telling the story from the Jabberwock's point of view. Take each situation as it comes.

And remember: nobody's perfect.

Clip art from Heraldic Crests by James Fairbairn.