Writing tips: The difference between “that” and “which”

My time with the wiki has taught me many valuable things, including the fact that I—as an American writer—have been using “that” and “which” erroneously. If you—like me—are in the habit of using the word that “sounds right,” rather than referring to your style guide, read on! This post may just have a tidbit or two of new information for you.

According to The Chicago Manual of Style, “which” is generally used with nonrestrictive clauses, while “that” is typically used with restrictive clauses.1 What are restrictive and nonrestrictive clauses, you ask? Let’s take a look at an example:

Cake, which is a very tasty dessert, is in the kitchen.

The cake that is covered in yellow frosting is in the kitchen.

The first sentence is an example of a nonrestrictive clause, while the second sentence is a restrictive clause. The Chicago Manual of Style notes that if you can take out part of the sentence without changing its meaning, you have a nonrestrictive clause.2 The clause “which is a very tasty dessert” adds additional information to the sentence but can be eliminated without changing the meaning of the sentence. Conversely, a restrictive clause is necessary to maintain the meaning of a sentence.3 Without the phrase “that is covered in yellow frosting,” the reader would not know which cake the writer is referring to.

Part of the reason why “that” and “which” are frequently used interchangeably is because, in British English, it’s acceptable to use “which” with restrictive clauses4:

Playgrounds which have tire swings are popular with elementary school students.

With American English, though, it’s considered best practice to set “which” off with commas and omit commas when using the word “that.” Because the wiki uses American English, you may notice that our posts adhere to this formula.

I hope this post has been helpful! The finer nuances of English can be deceptively difficult. When in doubt, review The Chicago Manual of Style, and be mindful of your specific audience (American-English speakers, British-English speakers, etc.).

Show 4 footnotes

  1.  “Which vs. That,” The Chicago Manual of Style Online, accessed June 8, 2018, http://www.chicagomanualofstyle.org/qanda/data/faq/topics/Whichvs.That.html
  2.  “Which vs. That,” The Chicago Manual of Style Online, accessed June 8, 2018, http://www.chicagomanualofstyle.org/qanda/data/faq/topics/Whichvs.That.html
  3.  “Which vs. That,” The Chicago Manual of Style Online, accessed June 8, 2018, http://www.chicagomanualofstyle.org/qanda/data/faq/topics/Whichvs.That.html
  4.  “Which vs. That,” The Chicago Manual of Style Online, accessed June 8, 2018, http://www.chicagomanualofstyle.org/qanda/data/faq/topics/Whichvs.That.html
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