First, Second, and Third Conditional

First, Second, and Third Conditional

Conditional type zero is used to talk about general truths, scientific facts or things which always happen under certain conditions.

Form:

If + Simple Present, + Simple Present

Use:

The zero conditional is used to talk about things which are always true, scientific facts, general truths:
Examples:

If you cross an international date line, the time changes.
Phosphorus burns if you expose it to air.
If I wake up early, I go jogging.
NOTE: you can use "when" instead of "if".

Conditional Sentence Type 1

Often called the "real" conditional because it is used for real or possible situations. These situations take place if a certain condition is met. It is possible and also very likely that the condition will be fulfilled.

Form:

If + Simple Present, + Simple Future

Use

Conditional Sentences Type 1 refer to the future. An action in the future will only happen if a certain condition is fulfilled by that time. We don't know for sure whether the condition actually will be fulfilled or not, but the conditions seems rather realistic – so we think it is likely to happen.
Example:

If I have enough time, I'll watch the football match.

I may have time to watch the match but I'm not sure about it.

Conditional Sentence Type 2

Often called the "unreal" conditional because it is used for unreal impossible or improbable situations. This conditional provides an imaginary result for a given situation. It is very unlikely that the condition will be fulfilled.

Form:

if + Simple Past, + would + base verb

Were / Was

In conditional type 2, we usually use in the if clause "were" instead of "was" even if the pronoun is I, he, she or it. "were" here is a subjunctive form.
NOTE "was" is also a possible form.

Example:

If I were a millionaire, I would buy a castle.

Use

Conditional Sentences Type 2 refer to an action in the present that could happen if the present situation were different. I don't really expect the situation to change because it is very unlikely.

Example:

If I had a lot of money, I would travel around the world.

Conditional Sentence Type 3

It is impossible that the condition will be met because it refers to the past.

Form:

if + Past Perfect, + would + have + Past Participle

Use

Conditional Sentences Type 3 refer to situations in the past. They express hypothetical results to past given situations.

1. First conditional
   1. Nature: Open condition, what is said in the condition is possible.
   2. Time: This condition refers either to present or to future time.
      e.g. If he is late, we will have to go without him.
      If my mother knows about this, we are in serious trouble.
   
   
2. Second conditional
   1. Nature: unreal (impossible) or improbable situations.
   2. Time: present; the TENSE is past, but we are talking about the present, now.
      e.g. If I knew her name, I would tell you.
      If I were you, I would tell my father.
      Compare: If I become president, I will change the social security system. (Said by a presidential candidate)
      If I became president, I would change the social security system. (Said by a schoolboy: improbable)
      If we win this match, we are qualified for the semifinals.
      If I won a million pounds, I would stop teaching. (improbable)
   
   
3. Third conditional
   1. Nature: unreal
   2. Time: Past (so we are talking about a situation that was not so in the past.)
      e.g. If you had warned me, I would not have told your father about that party.(But you didn't, and I have).     

1. First conditional:	If I have enough money, I will go to london chelsea.
2. Second conditional:	If I had enough money, I would go to london chelsea.
3. Third conditional:	If I had had enough money, I would have gone to london chelsea

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