The difference between defining and non-defining relative clauses is important to understand if you want to use relative clauses correctly.
Relative clauses add extra information to a sentence by defining a noun. However...
Let's take a closer look with some examples.
Defining relative clauses are crucial to the sentence. If the clause is removed, the sentence will not make sense and will not have the same meaning.
That is why they are also called essential relative clauses, essential meaning absolutely necessary or extremely important.
Let's take a look with some examples! (The relative clause is in red).
Now lets see what happens if we take out the relative clause:
As you can see the, the meaning of the sentences have been completely changed, or they don't really mean anything.
We now have questions about the noun:
Non-defining relative clauses, however, are not essential to the sentence. If the clause is removed, the sentence still makes sense and has the same meaning.
The information may of course be relevant, which is why it is included, but it is not the main point that the sentence is trying to convey about the noun.
If we now take out the non-defining relative clauses, the main idea of the sentence remains and the sentence still makes perfect sense.
You may have noticed another difference between defining and non-defining relative clauses, and that is with commas.
We'll look at commas and relative clauses in more detail in another lesson, but basically defining relative clauses have no commas and non-defining do have commas:
'That' is another important distinction in the difference between defining and non-defining relative clauses.
You may have noticed that some relative clauses use 'that' while others do not. The basic difference is that:
In fact, it is much more common to use that instead of which in defining relative clauses, but it can also replace who.