“It” can act as a regular pronoun (i.e., it refers to a noun) and can also act as a placeholder pronoun.
What do we mean by the term “placeholder pronoun”?
The term refers to a pronoun (“It”) that doesn’t refer to a noun and just holds a place in a sentence. For example:
It is nice that you are wearing jeans.
Is “it” referring to anything in the above sentence?
No. “It” is just holding the place of a noun – in the above sentence, “it” is holding the place of the subject.
Let’s look at a couple of more sentences:
1. It is safe for you to go outside.
2. I want to make it clear that I was not a part of this crime.
In both the sentences above, “it” acts as a placeholder pronoun. “it” doesn’t refer to any noun. “It” holds the place of the subject in the first sentence and holds the place of the object in the second sentence.
I have seen that the placeholder “It” is commonly used when infinitives or that-clauses are the subject (or the object) of a clause.
For example:
It is nice that you are wearing jeans.
What do you think is nice per the above sentence?
Answer: That you are wearing jeans.
Right?
Thus, meaning-wise, the that-clause is the subject. The above sentence is equivalent to the following sentence:
That you are wearing jeans is nice.
Both these sentences mean the same and are grammatically correct. However, the first sentence with the placeholder “it” is more common nowadays.
The sentence “
It is nice that you are wearing jeans” is an example of a sentence in which “it” acts as a placeholder and pushes the that-clause to the latter part of the sentence.
The same idea applies to infinitives.
It is safe for you to go outside.
What do you think is safe per the above sentence?
Answer: To go outside.
Right?
Thus, meaning-wise, the infinitive is the subject. Rather, the above sentence is equivalent to the following sentence:
To go outside is safe for you.
Both these sentences mean the same and are grammatically correct. However, the first sentence with the placeholder “it” is more common nowadays.
The sentence “
It is safe for you to go outside” is an example of a sentence in which “it” acts as a placeholder and pushes the infinitive to the latter part of the sentence.
Similarly, in the below sentence, the placeholder “it” pushes the that-clause (which is meaning-wise the object of “make”) to the latter part of the sentence.
I want to make it clear that I was not a part of this crime.
Here are a few more sentences with the placeholder “it” and their equivalent sentences without the placeholder “it”.
1. It is very difficult to tell the male and female apart in blue-winged warblers.
Equivalent Sentence: To tell the male and female apart in blue-winged warblers is very difficult.
2. It is perhaps surprising that the government decided to pass the bill.
Equivalent Sentence: That the government decided to pass the bill is perhaps surprising.
3. It is not decided yet whether I’ll visit the US in November.
Equivalent Sentence: Whether I’ll visit the US in November is not decided yet.
Are the above the only ways in which the placeholder “It” is used?
I don’t think so. There are other ways too. However, the above ways are some common ways in which the placeholder “It” is used.