There are five types of conditional sentences in English.

Conditional sentences are known as “if clauses”. All the conditional sentences consist of a condition and a consequence.

Conditional sentences are commonly used in English, therefore it’s important to understand how to use each type of conditional sentence.

First, we need to understand two terms: present conditional and perfect conditional.
The present conditional is: would/wouldn’t + verb (V1/base form)
The perfect conditional is: would/wouldn’t + have + past participle

What is zero conditional?

Zero conditional
This type of conditional refers to situations that are always true or possible. So we use the zero conditional when talking about things that are always true.

The sentence structure is ➜ If + present simple, present simple

For example: If you heat ice, it melts.

What is first conditional?

First conditional
This type of conditional refers to a situation that is possible or realistic in the present or the future. So we use the first conditional when talking about possibilities in the present or future.

The sentence structure is ➜ If + present simple, future simple

For example: If it snows, I will stay at home.

What is second conditional?

Second conditional
This type of conditional refers to a situation that is impossible or unlikely to happen. So we use the second conditional to talk about an imaginary situation in the present or future.

The sentence structure is ➜ If + past simple, present conditional

For example: If I were you, I would quit smoking.

What is third conditional?

Third conditional
This type of conditional refers to a situation that differs from reality. So we use the third conditional when talking about an imaginary situation in the past.

The sentence structure is ➜ If + past perfect, perfect conditional

For example: If the weather had been good, we would have gone to the park.

What is mixed conditional?

Mixed conditional
A mixed conditional is a conditional sentence with a mixture of the second and third conditionals.

If + 2nd conditional, 3rd conditional
We use this conditional sentence when talking about the present result of a past condition.
The sentence structure is ➜ If + past simple, perfect conditional

If + 3rd conditional, 2nd conditional
We use this conditional sentence when talking about the past result of a present or continuing condition.
The sentence structure is ➜ If + past perfect, present conditional

Comma rule

Remember to use a comma in the sentence if the ‘if clause’ is at the beginning of the sentence.
However, if the ‘if clause’ is at the end of the sentence; then, a comma is not required.