This document discusses different types of conditional sentences in English. There are three main types:
1) Type 0 or real conditional sentences use the present simple tense to describe general truths or facts. Examples are given such as "Water turns to ice if it freezes."
2) Type 1 or probable conditional sentences use the present simple in the if-clause and will/can + infinitive in the main clause to describe probable future events based on present conditions. An example is "If I study hard, I will pass the exam."
3) Type 2 or unreal conditional sentences use the past simple in the if-clause and would/could + infinitive in the main clause to describe improbable or hypothetical