Using if

If is a subordinating conjunction. It is mainly used to introduce a condition that must exist before something else can happen.

• If you don’t work hard, you will fail.
• If she is late, we will have to go without her.
• If she doesn’t pay the fee, she will not be allowed to take the test.

If clauses may also introduce a situation that may happen or may be real.

• If you miss this opportunity, you will have to regret later.

If you want / like

This expression is used to suggest that somebody has the freedom to do what they want.

• She can join us if she wants / likes.

If so

If so means ‘if this is true’.

• Do you like our lessons? If so, would you mind sharing them on your favourite bookmarking sites?

If can be used to introduce a situation that always produces the same result.

• If you heat ice, it melts.
• I always get a headache if I don’t sleep well.

Indirect yes / no questions

If is used to introduce indirect yes / no questions. Whether is also possible in this case.

‘Are you ready?’ Rani asked me.

Rani asked me if I was ready.

‘Do you like classical music?’ she asked.

She asked me if I liked classical music.

I still haven’t decided if I am moving to another city.