Parts of a sentence that identify people, things or add some additional information are called relative clauses.
They often begin with either a question word (who, what, where, which etc) or ‘that’. They can also start with pronouns; e.g. whose).
Examples of relative clauses:
- He is the man who lives next door to me.
- The journalist, whose work involves a huge amount of international travel, is currently in South America.
- My house, which is in the country, is not very big.
- Here’s the book that you wanted me to get.
Notice how the clause immediately follows the noun it relates to.
The game that they are playing originated from Southern Europe.
NOT: The game originated from Southern Europe that they are playing.
There are two common types of relative clause:
1. Defining relative clauses (also called ‘restricting relative clauses’ or ‘identifying relative clauses’)
2. Non-defining relative clauses (also called ‘non-restricting relative clauses’ or ‘non-identifying relative clauses’)
1. Defining relative clauses
A defining relative clause is one in which the clause is required for the understanding / grammar of the sentence.
Example:
She is the teacher who helped me with my homework.
If we remove the relative clause ‘who helped me with my homework‘, we are left with ‘She is the teacher’ which is not a complete sentence.
With defining relative clauses, we can change the question word for ‘that’:
She is the teacher that helped me with my homework.
2. Non-defining relative clauses
A non-defining relative clause is one in which the clause is NOT required for the understanding / grammar of the sentence. A non-defining relative clause adds extra information, but we can remove it and the sentence will still make sense.
Example:
My friend, who comes from Australia, loves surfing.
If we remove the relative clause, we are left with ‘My friend loves surfing.’, This a grammatically complete sentence.
NOTE: In non-defining relative clauses, we CANNOT change the question word for ‘that’.
Example:
My friend, that comes from Australia, loves surfing. We MUST use ‘who’.
In addition to not using ‘that’, non-defining relative clauses differ from defining relative clauses in that they use commas to show that the clause is not essential to the grammar of the sentence. Defining relative clauses do not use commas.
Compare:
She is the teacher that helped me with my homework.
She is the teacher, that helped me with my homework.
My friend, who comes from Australia, loves surfing.
My friend who comes from Australia loves surfing.