When editing your novel, short story, poetry, or essay, keep a sharp eye out for these tricky little grammatical errors that can crop up in nearly every writer’s work at some point. Should you write its or it’s? That or Which? Avoid grammatical errors by knowing the rules!

Its or It’s? What’s the difference between it’s and its?

It’s is a contraction of it and is.

I’m not sure if it’s going to be a success.

Its is possessive and shows ownership.

When bathing a dog, avoid getting water in its face until the end of the bath.

Remember, “it’s” never means anything else but “it is” or “it has.”

For “its,” try substituting “his”— if it doesn’t make sense, it should be “it’s.”

That or Which? What’s the difference between that or which?

Compare the following sentences:

We need to get the lawnmower that is in the garage.

We need the lawnmower, which is in the garage.

Here’s the rule: Use which for a nonrestrictive clause and that for a restrictive one.

For sentence #1, we are looking for the lawnmower that is in the garage, not the lawnmower in the garden shed or at the neighbor’s. Our choice is restricted to the lawnmower in the garage. The “that” clause is essential to the meaning of the sentence.

In sentence #2, we need the lawnmower, and by the way, it’s located in the garage. The “which” clause is much like an aside—it adds more information but is not essential to the meaning of the sentence.

Another rule for punctuating sentences that use that or which: Always use a comma to set off a nonrestrictive clause (which), and don’t use a comma if the clause is restrictive (that).

A few more examples:

He served her a slice a pizza, which she quickly devoured.

She chose the slice of pizza that had pepperoni.

I bought my music from Best Buy, which is my favorite CD retailer.

The music that I download legally is from Emusic.com.

The car that is covered in racing stripes has just come in first.

The car, which is covered in racing stripes, has just come in first.

These are just two of the grammatical errors the proofreaders at Writer’s Relief look for when giving our clients’ work a final once-over. Get an advantage over the competition and make sure your submissions are professional and polished!