Conditional Sentences or Conditional Clauses I,II ,III. They are used to express that the action in the main clause (without if / second clause) can only take place if a certain condition (in the clause with if/second clause) is fulfilled. There are three types of Conditional Sentences.
It is very likely that the condition will be fulfilled
Form: If +Subject+ Simple Present , Subject+will + Simple present
Example : If I have money, I will travel to all over the world.
2) Type II
It is very unlikely that the condition will be fulfilled
Form: If +Subject +Simple Past, Conditional I =(Would + Infinitive )
Example: If I had money, I would travel to all over the world.
3) Type III
It is impossible that the condition will be fulfilled. the condition depends to the past .
Form : If + Subject +Past Perfect , Conditional II =( Would +have +Past participle)
Example : If I had had money , I would have traveled to all over the world.