Many sentences with if are conditionals: they express a condition and a result. We use different tenses and different structures, depending on what we are trying to express.
Zero conditional:
If + a present tense + a present tense
- Used for general or scientific truths
First conditional:
If + present tense + will(or other modal) + bare infinitive
If + present tense + imperative
If you are having problems, speak to your bank manager.
If + present tense + imperative
- Used for real or likely situations
If you are having problems, speak to your bank manager.
Second conditional:
If + past(simple or continuous) + would(or other modal)+ bare infinitive
- Used for impossible, unlikely or hypothetical situations