The pronoun ‘it’ is used
1) For a young child; as,
- That baby broke its toy.
2) For lifeless things; as,
- There is a stone; throw it away.
3) For animal; as,
- The cat is licking its paw.
4) For weather or time; as,
- It’s seven o’clock.
- It is summer.
5) For referring something which was explained before; as,
- To buy this product conditions are applicable; and he knows it.
6) For standing for no noun and can be supplied from the verb; as,
- It rains. (The rain rains.)
7) For temporary subject; as,
- It is difficult to solve that example. (To solve that example is difficult.)
8) For emphasizing the noun or pronoun; as,
- It was you who tore the register.