Welcome back to the course. In this video, we're talking about relative clauses. There are basically two types of relative clauses. The first type is the defining relative clause. And the second type is the non defining relative clause. So let's look at what each of these are.

We're starting with the defining relative clause. Basically, a defining relative clause is a clause which is necessary in a sentence. Without this clause, the noun remains incomplete. So basically, the idea of the sentence remains incomplete. In other words, this type of relative clause defines the noun. The last thing that you need to know about the defining relative clause is that we don't use a comma before the relative pronoun.

So let's look at Example, to better understand all of this. Here's our example. Belgium is the country that sold the most coffee. Now the word that in this sentence is the relative pronoun. And you'll notice that the word that defines the noun that comes before it. In this case, it's defining the country.

In other words, we're clarifying which country Belgium is. It is the country that sold the most coffee. If you were to just stop this sentence right here, this sentence wouldn't really make any sense. Because then you would just be left with Belgium is the country. And that is an incomplete sentence. Belgium is which country?

What type of country? We need to clarify this noun to show the reader what exactly, we're talking about. So, that is what we mean by a defining relative clause. On the other hand, we have the non defining relative clause, or non defining relative clause is not necessary in a sentence. Why? Because the idea is still complete without it.

So we don't really need the non defining relative clause. Well, if we don't really need it, then why do we use it? We use it when we want to give extra information about the noun in a sentence. Sometimes, we want to extend the amount of information that we're providing about the noun. In this case, we use the non defining relative clause. The last thing to note about this clause is that with this clause, we do use a comma before the relative pronoun.

So let's look at an example of this. Belgium earned 1.7 million In euros from coffee sales, which made it the most profitable country. So you'll notice that if we wanted, we could have just stopped the sentence right here. Or we could have just said, Belgium earned 1.7 million euros from coffee sales. That's a complete idea. We don't have to continue the sentence, we could just stop right here.

However, we decided that we want to add some extra information. Keep in mind, this extra information is not necessary. We just want to provide this extra information anyway. So in this case, we've added the extra information with this relative pronoun here, which that's our relative pronoun. And we've added this non defining relative clause, the clauses which made it the most profitable country so we call this a non dual Defining relative clause because this type of clause does not define the noun, whereas in the defining relative clause, this clause that we've added here defines the noun that we're talking about. So that's the difference between the defining relative clause and the non defining relative clause.

Now, all relative clauses use some kind of a relative pronoun. So in this example, we've used the relative pronoun that, in this example, we've used the relative pronoun wage. And there are several other relative pronouns that we use with both the defining and non defining relative clauses. So let's explore what some of these relative pronouns are. We're going to start off with the relative pronoun who. So we use this relative pronoun when We refer to people.

So here's our example sentence. Sam's mother who lives in Scotland has six grandchildren. So notice that we use the relative pronoun who to talk about Sam's mother, Sam's mother is a person. So therefore, we use the relative pronoun who. On the other hand, if you want to talk about things in general, then you can either use which, or that in this example, we're using the relative pronoun which to refer to overgrazing. So our sentences overgrazing represented the primary cause of global land depletion, which accounted for approximately 30% of land degradation.

Next, if you want to refer to places, then you can use the relative pronoun where For example, you could say, the only country where the population declined was Australia. Notice that we're using the relative pronoun where to talk about country. In this case, that country is Australia, and Australia is a place. If you want to refer to a specific period of time, then you can use the relative pronoun when. So you could say, the period when mobile phones plummeted in demand was the month of December. Notice that we're using the relative pronoun when to talk about the period.

That period is the month of December. So we're talking about a certain period of time. If you want to refer to possession, then you can use the relative pronoun who's. For example, you could say the only country who's Sales declined was Yemen. So in this case, we're using the relative pronoun who's to talk about the country's sales. In this case, we're talking about Yemen sales.

Okay? So we're showing possession, who sales, whose sales are we talking about? We're talking about Yemen's sales. I also want to point out that most of the times when we use this relative pronoun hos, we usually use it to show the possession by a person. However, you could also use this relative pronoun to show the possession by a country or other nouns. Here's our final example.

If you want to refer to a certain reason, then you can use the relative pronoun why. So here's our example. The reason why they migrated to the nearby islands is not clear. So in this case, y is referring back to this reason here, it is clarifying which reason we're talking about. So those are all the relative pronouns. And this is how we use them to refer to different things.

Now let's talk about the use of commas in the relative clauses. So the first thing that I want you to notice is that whenever we have a non defining relative clause, we have to use a comma. So we've used a comma here, here, and here. Do you remember what the non defining relative clauses the non defining relative clause is when we're just giving extra information. It's not required. We don't have to do it.

Why? Because the sentence is already complete without it, so we don't need it. But we're just providing extra information anyway. So whenever we have an on defining relative clause, we use a comma. So our first example here is Sam's mother, who lives in Scotland has six grandchildren. The middle part who lives in Scotland is just extra information, we don't really need it.

If we were to remove this part and just say, Sam's mother has six grandchildren, that would be fine. That would be a complete idea. And we wouldn't really need this part anyway. However, if you choose to add this part in the middle, then you have to add a comma before it and after it, to show that it is a separate piece of information. In our next example, we have over grazing represented the primary cause of global land depletion, which accounted for approximately 30% of land degradation. Notice again, that we could just stop the sentence here.

We don't have to continue This sentence, however, we're just choosing to add extra information. And since we're choosing to add extra information, we have to use a comma. On the other hand, if you have a defining relative clause, then we don't use a comma. The defining relative clause is when we're clarifying what exactly we're talking about. The defining relative clause defines the noun. For example, in this sentence, the only country where the population declined was Australia.

The relative clause Where is defining the country that we're talking about? It is defining the noun. Okay, so we don't use a comma with the defining relative clause. In this sentence, the relative clause when is defining the period of time. In this sentence, the relative clause whose is defining the country. And in this example, the relative clause Why is defining the reason.

So in all of these cases, we don't use any commas. So that's all for this video. I'll see you in the next grammar section in which we're going to be combining all of the different elements of grammar that we've been learning so far. So I'll see you there.