Sometimes in English, the correct punctuation and word choice can make quite a big difference.
You might have heard the story about the English teacher who asks his students to punctuate the following series of words to form a grammatically correct sentence: “Woman without her man is nothing.” Amusingly, the men all wrote, “Woman, without her man, is nothing.” And at the same time, the women all wrote, “Woman: Without her, man is nothing.” This story emphasizes the importance of proper punctuation.
But did you know that something as simple as deciding whether to use “that” or “which” in a sentence can also make a big difference? What exactly is the difference between “that” and “which”? Both “that” and “which” can be used in many constructions, but the confusion usually arises when they are used in relative clauses.
The difference between “that” and “which”
To begin to understand the difference, we first must understand the two types of relative clauses: defining (or restrictive) and non-defining (or non-restrictive) relative clauses.
Defining relative clauses contain information essential to the meaning of the sentence. If this clause is not included, the meaning of the sentence will be greatly affected; in fact, it might not make any sense at all.
Let’s look at an example.
“I like the painting that is hanging above the couch.”
This is a defining relative clause because it provides important information about the specific painting I am talking about. I don’t like all the paintings in the house, but rather, I specifically like the painting that is hanging above the couch.
Contrastingly, non-defining relative clauses contain extra information that is not important to the meaning of the sentence.
Let’s look at an example.
“I live in New York, which is one of the biggest cities in the world.”
Notice that the relative clause provides extra information and that the sentence would still make sense if the relative clause were removed. Non-defining relative clauses are separated by commas at each end of the clause and thus are easily recognizable.
If I’m writing a biography about my life and I mention, “My sister, who is a fashion designer, lives in New York,” you can immediately know that I have one sister. She is a fashion designer, and she lives in New York. However, if I remove the commas and instead write, “My sister who is a fashion designer lives in New York,” you now know that I have more than one sister, and this relative clause is defining the specific sister I am speaking about.
If you’re very observant, you might have noticed from the above examples that the defining relative clause used the word “that,” and the non-defining relative clause used the word “which.” That’s the difference.
Now, let’s look at some examples where this can make a big difference.
Defining relative clause: The university that is in the center of the town has night classes.
Non-defining relative clause: The university, which is in the center of the town, has night classes.
In the defining relative clause, it can be assumed that there is more than one university in the town, and the one that is in the center of the town is the one that has night classes. In the non-defining relative clause, we can assume that there is only one university in the town, and it just happens to be in the center.
Defining relative clause: The bathroom that is located on the second floor was just redone.
Non-defining relative clause: The bathroom, which is located on the second floor, was just redone.
The defining relative clause implies that there is more than one bathroom in the house. The non-defining relative clause implies that there is only one bathroom, and it is on the second floor.
It’s quite amazing the difference that just one word can make.
If you found this guide helpful, think about who else could benefit from it. Do you have friends who mix up “that” and “which”? Share this guide with them to help them out.
Diane is an English teacher from New York with over four years of experience teaching English to students from all over the world. She provides personalized English lessons on Skype as the founder of Teacher Diane and teaches a series of popular video tutorials on YouTube. Be sure to check her out.