What is a conditional sentence?

A conditional sentence is a sentence structure commonly used in English when we want to talk about something (a result) that may happen ONLY IF something else happens first (a condition). The condition may be something real or unreal / hypothetical, and the result could a definite result, or just a possible / likely result.

The most common type of conditional sentence uses if. These are the easiest conditional sentences to form and understand. You could also use unless, when, after, before or as soon as. Here, we will focus on using conditional sentences with if.

There are 2 parts to a conditional sentence. These two parts are also called clauses. [A clause is any part of a sentence with a subject and a verb.]

Part 1 – the if or condition clause: the event that needs to occur; also called the dependent clause because it is not a complete sentence and is dependent on the 2nd part of the sentence.

Part 2 – the result or main clause, or what happens when the event in the if/condition clause occurs; also called the independent clause.

Either part can come first:

Changing the order of the clauses does not change the meaning; the two sentences above mean exactly the same thing.

There are 4 types of conditional sentences in English:

0 (zero) conditional – real / factual conditional

1st (first) conditional – future possible/real conditional

2nd (second) conditional – present unreal/hypothetical conditional

3rd (third) conditional – past unreal conditional