Zero conditional

When we talk about things that are generally or always true, we can use:

► If/When/Unless plus a present form PLUS present simple or imperative.

- If he gets there before me, ask him to wait.
- When you fly budget airline, you have to pay for your drinks and snacks.
- Unless you need more space, a small car is big enough for one person.

* Note that we are not talking about a specific event but something which is generally true.