Zero conditional

We use the zero conditional to talk about things that are always true.

Structure

The present simple is used in both clauses.

Example:

If you heat water, it boils.

When the sun goes down, it gets dark.

It lights up if you push that button.

First conditional

We use the first conditional when we talk about real and possible situations.

Structure

if + present simple and will + infinitive

Example: 

I’ll go shopping on the way home if I have time.

If it’s a nice day tomorrow we’ll go to the beach.

 Second conditional

The second conditional is used to talk about unreal or impossible things.

Structure

if + past simple and would + infinitive.

                                      could

                                      might

Example:

If I won a lot of money I’d buy a big house in the country.

Where would you live if you could live anywhere in the world?

If you didn’t smoke so much you’d feel a lot better.