“That” vs. “Which”

The difference between “that” and “which”, and how to choose between them, has been the subject of much debate. It took me a long time to finally understand the distinction, but once you do understand the difference, the clarity of your writing will improve significantly.

You can use this very simple rule of thumb: in most cases, the correct word you want to use to introduce a clause is that (not which), and whenever you use which, it must be preceded by a comma. The choice is between that or “[comma], which” — and if you’re not sure, use that.

So, why is that appropriate in most cases instead of which?  That is used to introduce restrictive clauses: clauses required for the sentence to be grammatically and logically sensible. Which, on the other hand, is used to introduce non-restrictive clauses: clauses that give additional information that is not necessary to the meaning of the sentence.

Consider the following sentence:

  • “My car that is parked out front is the Batmobile.”

In this sentence, the clause “that is parked out front” is restrictive — it helps define “My car” by identifying that although I have more than one car, the one parked out front happens to be the Batmobile.

Compare to this sentence:

  • “My car, which is parked out front, is the Batmobile.”

Notice the difference in meaning? In this sentence, which introduces a non-restrictive clause. This sentence tells you that I own only one car, and it’s the Batmobile. And, incidentally, it’s parked out front, but you didn’t need to know that for the meaning of “My car” to be clear.

There are several ways to make sure you get this right:

  • First, always use a comma before which and never use a comma before that. This will ensure that your reader knows that you intend which to be non-restrictive and that to be restrictive, as they should be.
  • Second, if you’re unsure, use that and not which.
  • Third, try removing the clause from the sentence. If it can be removed from the sentence without changing the logical meaning (if it’s extraneous, additional information), then use which; otherwise, use that.

Knowing proper grammatical style can help you in daily life, in your professional life, and on the SAT, ACT, GMAT, and GRE. If you are planning to do test prep for any of these tests, contact Bobby Hood Test Prep for more information!