It

'It': pronoun

It, the pronoun, is used to refer to a thing previously mentioned or easily identified.

• I don't want to try this food. It smells really bad.
• She took a quick look at the computer and noticed it was very old.

 

'It': empty or dummy

We can call it 'empty', which means it doesn't refer to anything in particular. The pronoun 'it' is used either a subject or an object:

• I really hate it when somebody smack their lips together.
• How long does it take him to get his work done?
• Oh my goodness! It is too late now. I have got to go home right away. 
• I guess it might snow today.

 

Anticipatory 'it'

Anticipatory 'it' is used in the subject or object position to refer to the real subejct or obejct, which appears later in the sentence. We use anticipatory 'it' especially when the real subject or object of the sentence is a phrase or clause such as -ing form, to + infinitive , and that + clauses:

• It's strange being back here again. (Anticipatory subject)
• It was nice to meet you. (Anticipatory subject) 
• It's interesting that penguins cannot fly. (Anticipatory subject)
• She made it a rule to work out on a regular basis. (Anticipatory object)
• I consider it an honor to be nominated. (Anticipatory object)

 

Anticipatory 'it': passive construction 

Anticipatory 'it' is used in passive constructions, where the doer or agent is considered relatively less important or unimportant in the statement:

• It is said that the corruption in the organization is acute.
• It is argued that the decision is a military matter.

 

Anticipatory 'it': hedging and softening

Anticipatory 'it' is used to soften or hedge a statement, making it less direct:

• It looks like televised trials are here to stay.
• It seems that all is not well at home.
• It appears that he has never met her before.

 

Anticipatory 'it': cleft sentences 

We can use 'it' in cleft sentences. 'It' is used as an anticipatory subject to emphasize a specific element of the sentence:

• It was in 1950 that China first invaded Tibet.
• It is in Korea that you can enjoy a variety of Kimchi.
• It was James who told me to send an email.