Uses of It
We use it for a thing, an action, a situation or an idea.
You've bought a new coat. It's very nice, (it = the coat)
Skiing is an expensive hobby, isn't it?
You have to fill in all these stupid forms. It's ridiculous. I find astrology fascinating. I'm really interested in it.
We use it to mean 'the unknown person'.
Did someone ring? ~ It was Vicky. She just called to say she's arrived safely.
We use it for the time, the weather and distance.
It's half past five already.
It's Sunday tomorrow. It was much warmer yesterday.
It's fifty miles from here to Brighton.
We also use it in structures with a to-infinitive or a that-clause.
It was nice to meet your friends.
It would be a good idea to book in advance.
It's important to switch off the electricity.
It's a pity (that) you can't come with us.