:
1. First Conditional (Type I)
it is a structure used for talking about possibilities in the present or in the future.
Type 1: if + present + future.
Example:
If I have the money, I will buy this car.
The main clause can also be at the beginning of the sentence. In this case, don't use a comma.
Example:
I will buy this car if I have the money.
2. Second Conditional (Type II)
it is a structure used for talking about unreal situations in the present or in the future.
Type 2: if + past + conditional
Example:
If I had the money, I would buy this car. (Since I do not have the money I cannot buy any new car). The action in type 2 is characterized by unreality.

3. Third Conditional (Type III)
it is a structure used for talking about unreal situations in the past. In other words, it is used to talk about things which DID NOT HAPPEN in the past.
Type 3: if + past perfect + perfect conditional
Example:
If you had driven more carefully, you would not have had an accident. (You had an accident because you didn't drive carefully enough.)
The action in type 3 is characterized by impossibility.
While type 1 and type 2 focus on the present or future, the time in type 3 is the past and signifies a completed action in the past. The condition, therefore, cannot be fulfilled because the action in the if-clause did not happen.

 
thank u alot dear