Zero conditional

This is the first in a series of posts about conditional sentences. That means sentences with "if". Let's start with the easiest one, the zero conditional, although you don't need to worry about the names as much as the meaning. Keep reading to learn more. 

We usually make the zero conditional with two present simple verbs. Use if, unless or when to join the two parts of the sentence.
Examples:
If I drink coffee in the evening, I can't sleep.
I feel better if I exercise every day.
I never watch TV in bed unless I am ill.
When I'm upset, I phone my best friend to talk about it.

When the linking word is at the beginning, you need a comma in the middle. There is no comma when the sentence is the other way round. (Oh, I've just written two more conditional sentences!!)
 
Note that if and when have the same meaning.
If you heat water to 100°C, it boils.
and
When you heat water to 100°C, it boils.
have the same meaning.

We sometimes use the present continuous:
I go for a walk every day unless it's raining.
Or present perfect:
I always sleep better if I've had a warm bath.
Or the imperative:
If you've had a drink, don't drive.

In all the sentences above, we are talking about something which is always, usually or often true. We use present tenses in the same way that we would in normal sentences and that's why this is the easiest conditional!

We can also talk about thing that were always true in the past and some people also call this the zero conditional. For example:
When the weather was good, I walked to school.
If it rained, my mum took me to school in the car.
We use the past simple in both halves of the sentence.

The main points to remember about the zero conditional are:
1. It describes something that is always true (or was always true)
2. It's real (not hypothetical)
3. We use the same tenses that we would use in a normal sentence. This is usually present simple in both halves but there are other possibilities.

You can read about the first conditional here and the second conditional here.