What is a Relative Clause?
A relative clause is a phrase that adds information to a sentence. All relative clauses describe a noun, and they begin with one of these relative pronouns or relative adverbs.
- who (to describe people – subject)
The woman who works in the bank is my neighbor.
- whom (to describe people – object)
My cousins, one of whom is a doctor, live in England.
- whose (to describe possession)
The man whose car was stolen went to the police station.
- that (to describe things – defining relative clauses)
I’m selling the computer that I bought in the U.S.
- which (to describe things – non-defining relative clauses)
I’m selling this computer, which has a 250-GB hard drive, for $500.
- when (to describe times)
My favorite season is fall, when all the leaves change color.
- where (to describe places)
I visited the neighborhood where I grew up
- why (to give a reason)
Do you know the reason why the stores are closed today?
Relative Clauses = Better Sentences in English
Here is an example of some English sentences without relative clauses:
- Yesterday I met a man. He works in the circus.
- I bought a cell phone. It has internet access.
- There’s the restaurant. I ate at that restaurant last night.
These sentences are correct, but they are very short and simple. You can use relative clauses to make your sentences in English sound more fluent and natural:
- Yesterday I met a man who works in the circus.
- I bought a cell phone that has internet access.
- There’s the restaurant where I ate last night.
Defining and Non-Defining Relative Clauses
Non-defining relative clauses add EXTRA information to the sentence.
Defining relative clauses add ESSENTIAL information to the sentence.
You can see if a relative clause is defining or non-defining by removing it from the sentence. If you remove a non-defining relative clause, the sentence still has the same meaning. If you remove a defining relative clause, the sentence has a different meaning or is incomplete.
Example of a sentence with a NON-DEFINING relative clause:
- My brother, who lives in California, is an engineer.
If you remove “who lives in California,” the sentence still has the same meaning:
- My brother is an engineer.
Example of a sentence with a DEFINING relative clause:
- That’s the student who failed English class three times.
If you remove “who failed English class three times,” the sentence is incomplete:
- That’s the student.
Therefore, the relative clause “who failed English class three times” is essential information, because it defines which student, specifically, we are talking about.
In written English, use a comma before and after non-defining relative clauses.
Which or That?
Use which for non-defining relative clauses, and use a comma before it.
Use that for defining relative clauses, and don’t use a comma before it.
- The bananas that I bought on Monday are rotten.
- The bananas, which I bought on Monday, are rotten.
In the first case, it’s possible that we have two types of bananas in the house:
- Older bananas that I bought on Monday
- Newer bananas that I bought on Wednesday
…and that only the first bananas are rotten, but the second bananas are not rotten.
In the second case, all the bananas in the house were bought on Monday, and they are all rotten.
Again, to decide if a clause is defining or non-defining, try removing it from the sentence:
- I read all the books that I borrowed from the library.
Without clause: I read all the books.
(sentence is incomplete – WHAT books?)
- The new Stephen King book, which I borrowed from the library, is very good.
Without clause: The new Stephen King book is very good.
(sentence is complete. The “library” part was only an extra detail)